Content area
Geographic Information Systems (GIS) merge the graphic features of a map with its associated data, and because of this, in-depth analyses of geographic relationships are possible. GIS is often defined by its method of storing data and features in layers, allowing users to overlay various types of information to view simultaneously. Because of the range of capabilities and limitations, the various mapping technologies currently available on the Web can be roughly separated into three categories according to user requirements, technology, and application capabilities in the library: high level, midlevel, and low level. Customized digital mapping is no longer limited solely to GIS users, since the Internet is rapidly becoming a forum for usable and simplified GIS operations. Libraries of all types may find these new technologies useful in reference, and librarians in all fields are encouraged to become acquainted with the appropriate resources applicable to their daily users.
Numerous types of geographic information management technologies are currently available on the Web, ranging from simple tools for viewing maps to more complex systems such as Geographic Information Systems (GIS). The term GIS is commonly applied to all automated mapping. However, it specifically describes a system of computer hardware, software, and geographically referenced data, designed to capture, store, edit, display, and plot spatial information.
Geographic Information Systems (GIS) merge the graphic features of a map with its associated data, and because of this, in-depth analyses of geographic relationships are possible. GIS is often defined by its method of storing data and features in layers, allowing users to overlay various types of information to view simultaneously. The number of automated mapping tools that share some, but not all, of these capabilities is increasing, and more and more information is being made available using geographic technologies.
Understanding the capabilities, benefits, and limitations of these tools can greatly enhance reference service in both traditional and virtual environments. In fact, familiarity with some of the geographical resources on the Web can answer many common reference inquiries. For example:
Maps effectively illustrate data. For instance, if a researcher is seeking the latest population numbers for a particular neighborhood, a map of that area in the context of the entire city with associated statistics is more helpful. Similarly, a map of Superfund locales or toxic release sites can be more effective than a listing, as a visual display of the highest concentrations of harvested croplands or forest cover types is preferable to a description.
Maps act as alternative finding aids, particularly when features are more easily identified graphically. GIS technologies commonly have clickable maps that link locational information to pertinent data. For instance, a prospective homebuyer can research what houses in a neighborhood last sold for and when by selecting the properties. A hiker can check the land elevation of the area before setting off on a trip, or a citizen can find details on the aquifer supplying municipal water, all by pointing at a map.
Geographic technologies can combine several variables in a single, custom-made map. For instance, public officials can not only assess the adequacy of public transport to local health facilities by overlaying city bus lines onto a map of clinics and hospitals, but they can also map their districts according to race and income levels from the latest census. Similarly, a researcher can check mortality rates in the United States by specific types of cancer, and this according to race, gender, or a number of other factors.
GIS Resources: A Profile of Types Available
GIS and mapping technologies can refer to a number of different types of Web tools, all serving different functions. Because of the range of capabilities and limitations, the various mapping technologies currently available on the Web can be roughly separated into three categories according to user requirements, technology, and application capabilities in the library: high level, midlevel, and low level.
The high-level user has specific needs, is proficient with computer use, and is rather well informed about the type of information she or he seeks. Unsurprisingly, the technology required is also the most advanced; GIS software is used off-line, and the Web functions as a means to locate and retrieve data from databases of geospatial metadata. The Internet is also often used at this level to find and download additional GIS applications. The midlevel user is comfortable with using the Web and has some specific questions, but needs assistance locating relevant information sources. Technologically, the tools at this level represent the growing number of dynamic map applications available on the Web. These applications are structurally simplified GIS and have some of its capabilities, but are designed for very limited purposes, such as driving directions, environmental conditions, transportation routes, or any other type of geographical information. The low-level user has a simpler information need that does not require in-depth knowledge of electronic mapping. Databases of static images that include maps constitute this type of technology; though functionality and user-interaction are minimal, it is most appropriate for many map needs. A few examples will be cited for each of the three levels; however, in-depth descriptions and evaluations of the more prominent resources may be found in the library literature and online directories and guides.1
High Level
"I want to make a map of outdoor camping facilities in Minnesota by county using this table of data I collected." This request exemplifies a need answered by high-level GIS tools. The patron will need (1) georeferenced spatial files of the state, with county boundaries; and (2) access to GIS software, such as ArcView or MapInfo. The former can be found using a database on the Web, likely through a state agency, and then downloaded to a local computer. Once the files are decompressed and opened in GIS software such as ArcView or MapInfo, the user's table could be automatically matched to the map information, and a map combining the information created.
As mentioned earlier, GIS is a group of complex, multi-filed systems with advanced capabilities associated with analyzing and displaying large amounts of data geographically. As a result of increased affordability and technological advances that have moved it to the desktop, more and more people are utilizing it as a resource. The availability of spatial data libraries on the Web has also increased accessibility, creating common access to files that in the past would have been costly as well as difficult to locate and identify. Trends in commercial GIS are toward exploiting the plethora of data via networks and promoting data sharing.
The Internet is invaluable as a source of data for GIS users; online files, with standardized data, may be located and downloaded for incorporation and manipulation within GIS software off-line. The burdens associated with locating suitable data in compatible formats have been eased by the increased documentation, organization, and sharing of geospatial data that occurs via the Web. In 1998, the Federal Geographic Data Committee updated the 1994 Content Standard for Geospatial Metadata, which essentially mandates the construction of metadata, or information about information.2 U.S. government and many states data therefore reflect this mandated structure, though MARC and Dublin Core standards are commonly applied elsewhere.3 In all cases, guidelines are designed to ensure that descriptions of data origin, format, and content are sufficient for a user to determine its usability, including where, when, and how data were collected. Librarians have a similar cataloging system, with the significant distinction that these records are created by data producers.
In the past five to ten years, there has been a great deal of collaboration and effort toward sharing metadata, resulting in meta search engines or clearinghouses of geospatial databases. A combination of online geographic data sources can be searched this way-from sites compiled by federal, state, or local government agencies as well as commercial software vendors.4 A user can search by keyword, location, originating agency, or even by using an interactive spatial browser, which is the electronic equivalent of a print map index. Many records contain live links so one can immediately download files. Use of databases and data from federal and state governments continues to be free of charge, and the commercial geographic community is slowly following suit. The most prominent large-scale example is the Geography Network by Environmental Systems Research Institute (ESRI), a project cataloging data from disparate sources worldwide, much of it free.5 The Minnesota Geographic Data Clearinghouse is an example of a successful state government organization allowing searching of a network of data libraries. This movement on the part of governments and commercial vendors toward documenting geospatial datasets and making them available in a shared, user-friendly environment has decreased the need for recreating files or purchasing datasets, thereby promoting geographic research and expanding the use of the technology.
Though use of the Internet at this high level is primarily associated with locating digital geospatial datasets, new and less-visible trends in geographic technologies promise even closer ties between GIS and the Internet. In the commercial world, ArcGIS (ArcView 8.x and ArcInfo 8.x), a newly released GIS product from ESRI, combines the functionality of GIS with the data searching and access capabilities of the Internet. In this case, GIS software is used to access data from remote servers using metadata written in eXtensible Markup Language (XML) and is referred to as net-savvy GIS software.6 Another means by which this tier has a presence on the Web is via the distribution of free and open source software applications, viewers, and extensions, which are feasible alternatives for highly-skilled users.
Applications in the Library
The availability of GIS in libraries is relatively limited and does involve some specialized knowledge, but it is increasing in all types of institutions. Collections of government publications make up perhaps the largest single group with a real demand, as the transition of the Federal Depository Library Program to a primarily electronic environment in the 1990s made familiarity with digitally stored information imperative. Though this trend began with magnetic tapes and CD-ROMs, the release of 2000 census results as datasets and map files on the Web necessitated Internet proficiency for librarians and users alike. Other libraries with a demand for GIS resources include map collections and special libraries for businesses or research institutes, though those within larger institutions are by far the most likely to offer GIS. The St. Louis Public Library and the libraries of the University of Minnesota and Princeton University all maintain separate, fully equipped computer facilities and fileservers devoted to GIS.7 Others may offer GIS software on a single machine, available with staff assistance or by appointment. In addition to housing electronic data, many of these institutions place data of local interest on their Web servers or simply maintain a page of links to relevant data producers.
While files useable in GIS can sometimes be found free on the Web, the costs associated with offering facilities for full-fledged GIS can be fairly intensive. Until recently, high-level GIS applications were altogether inaccessible to most libraries due to the prohibitively high cost of the specialized hardware and software required, but this has changed. For libraries, a single copy of the ESRI ArcView 8.1 software can be obtained for $250, though hardware demands can still keep the cost prohibitive.8 Staff time and training is considerable. Libraries with an interest in establishing service in this area should consult the literature?
Midlevel
"I'm researching the socioeconomic makeup of a region across the country and would like to look at a map showing demographic features of the area." The patron with this request can be helped using midlevel geographic technologies. She or he could be pointed to the National Atlas of the United States available from the U.S. Department of the Interior or the U.S. Census Bureau's American Factfinder.10 Both federally produced tools allow the user to select the features to include on the map from among available data. A good computer with access to the Web via a browser would be needed.
At the midlevel, GIS technologies have been moving to the Web via interactive mapping applications. These are dynamic mapping tools, the most advanced of which have the spatial query and analysis features of GIS while requiring no special knowledge or training to use. In these applications, the end user submits requests via a Web browser, which then communicates with a remote GIS containing all geographic data and feature information. Users interact with a data-inclusive, customizable map application without leaving their Web browser. Data and graphics are organized into thematic layers of geographic features that may be turned on or off (included in or excluded from the display), and multiple spatial layers that may be displayed simultaneously. Individual features have identity and, oftentimes, statistical data attached, and functions such as browsing, panning, identifying features, zooming, and querying are allowed. These mappers are essentially Web applications displaying predetermined, stored data, and the applications may use commercial software, the most common of which is ArcIMS; it may also employ some type of public domain software called freeware.11
Software and technology for the creation of online mappers have in recent years become accessible both economically and technologically, and their use has multiplied. Interactive maps are already an important means of disseminating information for federal and state governments. For example, the U.S. Environmental Protection Agency, the U.S. Geological Survey (USGS), and the U.S. Census Bureau are among the many federal government agencies using interactive map generators on the Web to distribute data.2 These sites are all designed primarily to allow users to create maps inclusive of statistical data and boundaries on the fly, and they use one or more commercial products to power their application and prepare data. Several state governments and agencies-including Arkansas, Maine, and Minnesota-also operate interactive mappers but often in partnership with other institutional and research organizations and using a combination of federal and state data.13 Other states, such as Kentucky and Virginia, maintain electronic atlases, providing search and data retrieval rather than interactive mapping.14
It is no longer prohibitive for smaller projects, such as those operated by educational institutions, local governments, and nongovernmental organizations, to utilize online GIS to disseminate information.15 Research institutes at universities commonly offer Web mapping. GRASSLinks, a project of the University of California at Berkeley, emerged as one of the first mappers on the Web in the mid-1990s, and offers public access to environmental data.16 This system uses a freeware called GRASS, developed and produced by the U.S. Army Corps of Engineers for its internal GIS.17 The Nature Conservancy, Council on the Environment of New York City, and Global Forest Watch are examples of nonprofit organizations using interactive mappers online to educate and inform.18 More local government agencies are exploiting the capabilities of online mappers. The Twin Cities metropolitan area of Minnesota is served by MetroGIS, a collaborative organization for data and mapping, and the online interactive mapper portion, Datafinder, is an award-winning service using commercial software and offering local data.19 Portland, Oregon, implemented a neighborhood crime mapping application called CrimeMapper to allow the general public to track locations and types of offenses in 2001.20 Story County, Iowa, is one among a growing number of county government agencies posting public cadastral information on the Web with the goal of alleviating some of the public service pressure on offices while providing an improved vehicle for public access.21
Web users most likely are introduced to online mapping by commercial endeavors. These are usually fairly simple in terms of the amount of data provided. Tools such as Microsoft Expedia, MapQuest, and MapBlast are designed to aid navigation.22 They provide street maps, directions, and, oftentimes, additional layers of information such as locations of sponsoring restaurants, banks, RV sites, and other commercial endeavors. Most commercial interactive maps are not interactive, but are simply mapmakers: they provide maps of requested areas but there is no user manipulation of the given map or its content. Such is the case with National Geographic Map Machine, Lonely Planet's Worldguide, and many other tools that will be discussed with the low-level categorization.23
Applications in the Library
Because of the capabilities of this direct Internet mapping and the vast amount of information available, midlevel mapping resources are particularly useful for reference service in the library. Patrons, even proficient users of the Web, are often simply not aware that these tools exist, but the flexibility, user-friendliness, and customization they offer recommends them for many geographical queries. Most patrons use high-level GIS in libraries for simple mapmaking and do not need its immense capabilities. Thus online mappers often satisfy user needs while mitigating the demand for unnecessarily intensive GIS software. A possible disadvantage for some libraries is that the high functionality and graphics require an up-to-date Web browser and a speedy connection, as well as support for frames or plug-ins like JavaScripts and Java. The recommended minimum screen resolution is often 800 by 600 pixels. Libraries with limited equipment also need to consider that most users will want printing capabilities, particularly in color, for the maps they are downloading.
Low Level
"I need maps of China, both current and from other points in the twentieth century." Using low-level tools, a variety of maps may be easily located and viewed. In this case, private or institutional (though still free) Web sites would be good sources. The David Rumsey Historical Map Collection, a private collection of historical maps offering more than six thousand images online, and the Perry-Castaneda Library Map Collection of the University of Texas at Austin both provide access to excellent archives of maps.24 A good computer with access to the Web via a browser would be needed.
Low-level technology includes searching and viewing images and maps on the Web. The Web is widely used by libraries, museums, and historical societies to display all sorts of visual collections, including photographs, art, ephemera, illustrations, objets d'art, and even newspapers and books. In all cases, an online database is constructed of descriptive records with links to the scanned-in images as raster files, most often in JPEG, PDF, or GIF format. Users conduct textual searches by querying a database of metadata, much like searching a library OPAC. Once the images are retrieved, however, user interaction ends, since there is no manipulation of the image online. Unlike the previous map tools discussed, images are static graphic files.
For cartographic collections, this level of tool is appropriate for historical maps and remotely sensed imagery, where the object itself is of primary interest. Thus, a lowlevel user is satisfied by predrawn maps and is usually seeking general information. There are advantages associated with using these tools: because they offer digitized images of paper maps, bibliographic information about the item is usually complete. This type of tool is readily accessible and demands minimal computer skills and standard software. Some databases have been equipped with features to create a degree of interactivity with the images via HTML, Java, and applets. For instance, a user can zoom in on an image by selecting a screen size or file size. Some databases also allow graphical searching with an HTML image map of a cartographic index.
The need for photographic images of antique or historical maps is clear: users wish to examine the original document. Many historical libraries, collections, and museums are increasingly creating digital reproductions of their holdings and posting them to the Web, usually as a part of digital library projects. Hundreds of maps from the Geography and Maps Division of the Library of Congress are presented in the American Memory, part of the National Digital Library Program.25 Sanborn Fire Insurance Maps are a well-known series of maps showing building footprints in American cities; these were recently digitized, put online, and are accessible by paid subscription.26 These visual databases are a boon for genealogists, historians, and educators. This is also ideal for those seeking predrawn, contemporary maps of all types, such as general reference maps or road maps, desired as-is for reference or printing without any need for analysis or customization.
Aerial photography and satellite imagery are common information needs handled by map libraries and may often be satisfied using the Web. Various commercial vendor services, such as Microsoft TerraServer, TopoZone, and MapMart store government-prepared maps and imagery using attractive and user-friendly browsers with search engines and viewers.27 These electronically index a vast data store of USGS imagery and are free of charge. However, if the user desires higher resolution via electronic or hard copy, it must be purchased. Local governments are good sources for aerial photography. The state of Minnesota's Department of Natural Resources has several online tools for viewing current Digital Orthophoto Quadrangles (DOQs) for the state-aerial photographs that have been georectified-as well as satellite imagery, USGS topographic quandrangles-- Digital Relief Grids (DRGs), and land use and ownership maps.28 Often this imagery is integrated into an online mapper (see above) enabling it to be viewed and overlaid with other information while remaining static images. Low-level map tools are also commonly used by location-- oriented services, such as the travel industry, conferences, and weather services.
Applications in the Library
Low-level mapping technologies can be beneficial to collections by taking pressure off public service staff and sparing the items themselves from wear and tear. However, disadvantages to this type of tool, even when selected appropriately, lie primarily with limitations of library equipment and facilities. Often, patrons desire a copy of the map and may be disappointed with the quality or size restraints of the printed image. The resolution of graphic files also can be unclear and grainy. Libraries with computers with small server space or Internet connections may find that loading large, high-resolution imagery is cumbersome and time consuming. On the other hand, smaller graphic files are often low-quality, lacking acceptable resolution.
Conclusion
Customized digital mapping is no longer limited solely to GIS users, since the Internet is rapidly becoming a forum for usable and simplified GIS operations. Libraries of all types may find these new technologies useful in reference, and librarians in all fields are encouraged to become acquainted with the appropriate resources applicable to their daily users. Libraries are increasingly incorporating decentralized, virtual resources into their own collections. Accessing nontextual information is a new challenge requiring special effort from librarians. Like most Internet technologies, these can be applied in numerous ways, including distance education delivery, and virtual reference. The geographic technologies were highlighted in three categories to promote thinking about ways in which geographic information and mapping resources may be incorporated into library service. By explicating how each works and providing brief summaries of the type of information available and its use, it is hoped that the types of tools most feasible and useful for the staff and users of their institutions may be better identified by librarians. It is also meant to encourage further thinking and creativity in the application and use of such technologies.
References and Notes
1. For descriptions and evaluations of some specific tools, see Brenda G. Mathenia, "Maps and Mapping Resources," College and Research Libraries News 62, no. 9 (2001): 910-12; Mary Lynette Larsgaard, "The World at Your Fingertips: Map Resources," Library Journal 124, no. 12 (1999): 57-60; Luigina Vileno, "Geography Resources on the Internet," College and Research Libraries News 7, no. 7 (1997): 471-74. There are many Internet directories with links to online mapping sources, among them: Edgewood College, Free Access Maps and Map Query Sites in Geographic Information Systems: A Tool for Inquiry-Based Education. Accessed Feb. 21, 2002, http:// danenet.wicip.org/gisedu/gisreslist.htm; Harvard Map Collection. Resource List, Interactive Maps. Accessed Feb. 21, 2002, http://icg.harvard.edu/-maps/cart/cartintr.htm; University of Delaware Library, Cartographic Information, Maps, and Spatial
Data: A Guide to Internet Resources. Accessed Feb. 21, 2002, www2.lib.udel.edu/subj/maps/internet.
2. Federal Geographic Data Committee, "Content Standard for Digital Geospatial Metadata (revised June 1998)," Federal Geographic Data Committee, FGDC-STD-001-1998. Washington, D.C. Accessed Feb. 21, 2002, www.fgdc.gov/metadata/ contstan.html.
3. Discussion of standards in David Y. Allen et al., "Metadata Primer for Map Librarians," MAGERT Electronic Publication Series No. 3 (2001). Accessed Feb. 4, 2002, www. sunysb.edu/libmap/metadata.htm.
4. Notably ArcData Online, accessed Feb. 4, 2002, www.esri.com/data/online/browse.html, and Geography Network, accessed Feb. 4, 2002, www.geographynetwork.com, both by ESRI.
5. Environmental Systems Research Institute, Geography Network. Accessed Feb. 4,2002, www.geographynetwork.com.
6. Brandon Plewe, GIS Online: Information Retrieval, Mapping and the Internet (Santa Fe, N.M.: Onword Pr., 1997).
7. All facilities are open to the general public.
8. As of January 2002, library use is restricted to instruction and research purposes. A single commercial copy costs $1,500. The final recommendation for ArcView 8.1 made on the GIS Users' electronic discussion list was: "CPU: As fast as you can afford, 733MHz or faster; RAM: 256MB or as much as you can afford up to IGB+; Drives: Fast high rpm (10,000+) 160MB throughput SCSI; 64MB video (no less than 32mb opengl)" according to the archived "Minimum Requirements for Hardware vs. Recommended." May 3, 2001. Accessed Feb. 4, 2002, http://library.usask.ca/lists/carta/2001/0013.html. As of 2001, purchasing equipment at this level cost around $3,000. ESRI, in the technical paper Performance Tips and Tricks for ArcGIS Desktop 8.1 (http://arconline.esri.com/arconline/ whitepapers/ao-/8.1_Performance_Tips.pdf, accessed Feb. 21, 2002) suggests hardware configuration with 450MHz, 128MB Ram (256MB recommended), SCSI drives.
9. For case studies of GIS services offered in libraries, see Jeanne Boston et al., "The Public Electronic Library: Integrating GIS Resources and Tools," Library Hi Tech 63, no. 3/4 (1998): 100-106; Lixin Yu, "Geographic Information Systems in Library Reference Services: Development and Challenge," The Reference Librarian 60 (1998): 87-110; Ronald C. Jantz, "Geographical Information Systems at Princeton University: Evaluation and Exploration of a New Service," Collection Building 16, no. 3 (1997): 125-36; Denise Stepens, "Managing the Web-enhanced Geographic Information Service," The Journal of Academic Librarianship 23, no. 6 (1997): 498-503.
10. U.S. Department of the Interior. Accessed Feb. 21, 2002, www.nationalatlas.gov. U.S. Census AmericanFactFinder. Accessed Feb. 21, 2002, http://factfinder.census.gov.
11. Internet Map Server (IMS) by ESRI.
12. U.S. Environmental Protection Agency EnviroMapper. Accessed Feb. 4, 2002, www.epa.gov/enviro/html/mod; U.S. Geological Survey, National Atlas of the United States. Accessed Feb. 4, 2002, http://nationalmap.usgs.gov.
13. The Arkansas Interactive Mapper, Center for Advanced Spatial Technologies, University of Arkansas. Sponsored by NASA. Accessed Feb. 5, 2002, http://Web.cast.uark.edu/local/ mapper. Internet Mapping, Maine Office of GIS. Accessed Feb. 5, 2002, http://apollo.ogis.state.me.us/mapping/mapintro.asp.
LandView, Minnesota Department of Natural Resources. Accessed Feb. 19, 2002, http://maps.dnr.state.mn.us/landview.
14. University of Kentucky. Kentucky Atlas and Gazetteer. Accessed Feb. 21, 2002, www.uky.edu/KentuckyAtlas. The Online Statistical Atlas of Virginia, Geospatial and Statistical Data Center, University of Virginia. Accessed Feb. 19, 2002, http://fisher.lib.virginia.edu/va-statlas.
15. Projects described in the literature include Yafang Su, Joan Slottow, and Avi Mozes, "Distributing Proprietary Geographic Data on the World Wide Web-UCLA GIS Database and Map Server," Computers and Geosciences 26, no. 7 (2000): 741-49; R. Kingston et al., "Web-based Public Participation Geographical Information Systems: An Aid to Local Environmental Decisionmaking," Computers, Environment, and Urban Systems 24, no. 2 (2000): 109-25.
16. GRASSLinks. Accessed Feb. 4, 2002, www.regis. berkeley.edu/grasslinks.
17. Other freeware systems include MapServer from the University of Minnesota. Accessed Feb. 4, 2002, http:// mapserver.gis.umn.edu. Also GeoTools. Accessed Feb. 21, 2002, http: / /geotools.sourceforge.net.
18. The Nature Conservancy. Accessed Feb. 4, 2002, http:// tncgis.env.duke.edu/data/IMS; Council on the Environment of New York City. Accessed Feb. 4, 2002, www.cenyc.org; Global Forest Watch. Accessed Feb. 4,2002, www.globalforestwatch.org.
19. Datafinder. Accessed Feb. 4, 2002, www.datafinder.org.
20. Portland, Oregon, CrimeMapper. Accessed Feb. 4, 2002, www.portlandpolicebureau.com.
21. Story County Iowa, Story Assessor. Accessed Feb. 6,2002, www.storyassessor.org/pmc.
22. Microsoft Expedia. Accessed Feb. 4, 2002, www.expedia. com; MapQuest. Accessed Feb. 4, 2002, www.mapquest.com; MapBlast. Accessed Feb. 4, 2002, www.mapblast.com.
23. National Geographic Map Machine. Accessed Feb. 4, 2002, http://plasma.nationalgeographic.com/mapmachine; Lonely Planet's Worldguide. Accessed Feb. 4,2002, www.lonelyplanet.com/destinations.
24. The David Rumsey Historical Map Collection. Accessed Feb. 21, 2002, www.davidrumseycom. Perry-Castaneda Library Map Collection of the University of Texas at Austin. Accessed Feb. 21, 2002, www.lib.utexas.edu/maps.
25. The American Memory, part of the National Digital Library Program. Accessed Feb. 4,2002, http://memory.loc.gov. 26. ProQuest Information and Learning, Digital Sanborn Maps,
1867-1970. Accessed Feb. 21, 2002, http://sanborn.umi.com.
27. Microsoft TerraServer. Accessed Feb. 4, 2002, http:// terraserver.homeadvisor.msn.com. TopoZone. Accessed Feb. 4, 2002, www.topozone.com. MapMart. Accessed Feb. 4, 2002, www.mapmart.com.
28. The state of Minnesota's Department of Natural Resources. Accessed Feb. 4, 2002, www.dnr.state.mn.us/ information_Center/maps.html.
Kimberly C. Kowal
Kimberly C. Kowal ([email protected]) is the Assistant Map Librarian at the John R. Borchert Map Library of the University of Minnesota Libraries, Minneapolis.
Copyright American Library Association Sep 2002