Seirup, L., and G. Yetman (20060531), U.S. Census Grids (Summary File 1), 2000, NASA Socioeconomic Data and Applications Center (SEDAC), Palisades, NY,
http://sedac.ciesin.columbia.edu/data/set/usgrid-summary-file1-2000 Seirup, L., and G. Yetman (20060531), U.S. Census Grids (Summary File 1), 2000: Metropolitan Statistical Areas, NASA Socioeconomic Data and Applications Center (SEDAC), Palisades, NY,
http://sedac.ciesin.columbia.edu/data/set/usgrid-summary-file1-2000... Seirup, L., and G. Yetman (20060531), U.S. Census Grids (Summary File 3), 2000, NASA Socioeconomic Data and Applications Center (SEDAC), Palisades, NY,
http://sedac.ciesin.columbia.edu/data/set/usgrid-summary-file3-2000