Brewer, C. & Suchan, T., (2001). Mapping census 2000: The geography of U. S. diversity. U. S. Census Bureau, Census Special Reports, Series CENSR/01-1. Washington, D. C.: U.S. Government Printing Office.
Chrisman, N. (1997). Exploring geographic information systems. New York: John Wiley & Sons, Inc.
Chrisman, N. (2002). Exploring geographic information systems. (2nd ed.). New York: John Wiley & Sons, Inc.
Microsoft Corporation. (2006). MapPoint 2006. Retrieved April 27, 2006, from http://www.microsoft.com/mappoint/default.mspx (Expired link archived at https://web.archive.org/web/20060416145609/http://www.microsoft.com/mappoint/default.mspx).
Monmonier, M. (1995). Drawing the line: Tales of maps and cartocontroversy. New York: Henry Holt and Company.
Oregon State University. Information Services. (n. d.). Government information sharing project. Retrieved July 19, 1999, from http://govinfo.kerr.orst.edu (since retired).
Pennsylvania State University. University Libraries. Social Science Library. Census Extractor and Locator Sites. Retrieved July 19, 1999, from http://www.libraries.psu.edu/crsweb/docs/extract.htm (since retired).
Roberts, S. (1994). Who we are: A portrait of America based on the latest U.S. census. New York: Times Books.
Speer, G. (1998). The metric system. Retrieved July 19, 1999, from http://www.essex1.com/people/ speer/metric.html (since retired).
Steger, T. D. (1986). Topographic maps. Washington D.C.: U.S. Government Printing Office.
Stevens, S.S. (1946). On the theory of scales of measurement. Science, 103, 677-680.1
U.S. Census Bureau (n. d.). Retrieved July 19, 1999, from http://www.census.gov
U.S. Census Bureau (1996). Federal expenditures by state for fiscal year 1995. Retrieved May 9, 2006, from www.census.gov/prod/2/gov/fes95rv.pdf
U.S. Census Bureau (2005). American FactFinder Retrieved July 19, 1999, from http://factfinder.census.gov
U.S. Census Bureau (2008). A Compass for understanding and using American Community Survey data: What general users need to know. U.S. Government Printing Office, Washington DC, 2008.