APA (7th ed.) Citation

Hills, R. C. (1899). Geologic atlas of U.S: Elmoro folio, Colorado. [publisher not identified].

Chicago Style (17th ed.) Citation

Hills, Richard C. Geologic Atlas of U.S: Elmoro Folio, Colorado. Washington, D.C.: [publisher not identified], 1899.

MLA (9th ed.) Citation

Hills, Richard C. Geologic Atlas of U.S: Elmoro Folio, Colorado. [publisher not identified], 1899.