United States. Bureau of the Census. cartographic Maps. lcgft https://id.loc.gov/authorities/genreForms/gf2011026387 Washington, U.S. Govt. Print. Off., 1971. eng Includes "County location index." Scale ca. 1:750,000. Oklahoma--Administrative and political divisions--Maps. United States Oklahoma. Available also through the Library of Congress Web site as a raster image. https://hdl.loc.gov/loc.gmd/g4021f.ct011166 URN:ISBN: