Unidentified

Chicago citation style
War Department. Office of the Chief of Engineers. U.S. Geological Exploration of the Fortieth Parallel. 1867-1881. Unidentified. 1868. Retrieved from the Digital Public Library of America, http://catalog.archives.gov/id/519636. (Accessed October 21, 2018.)
APA citation style
War Department. Office of the Chief of Engineers. U.S. Geological Exploration of the Fortieth Parallel. 1867-1881, (1868) Unidentified. Retrieved from the Digital Public Library of America, http://catalog.archives.gov/id/519636
MLA citation style
War Department. Office of the Chief of Engineers. U.S. Geological Exploration of the Fortieth Parallel. 1867-1881. Retrieved from the Digital Public Library of America <http://catalog.archives.gov/id/519636>.
Note: These citations are programmatically generated and may be incomplete.