APA (7th ed.) Citation

Geological Survey (U.S.) & Wilmarth, M. G. (1925). The geologic time classification of the United States Geological Survey compared with other classifications, accompanied by the original definitions of era, period and epoch terms. Department of the Interior, United States Geological Survey.

Chicago Style (17th ed.) Citation

Geological Survey (U.S.) and M. Grace Wilmarth. The Geologic Time Classification of the United States Geological Survey Compared with Other Classifications, Accompanied by the Original Definitions of Era, Period and Epoch Terms. [Washington, D.C.]: Department of the Interior, United States Geological Survey, 1925.

MLA (9th ed.) Citation

Geological Survey (U.S.) and M. Grace Wilmarth. The Geologic Time Classification of the United States Geological Survey Compared with Other Classifications, Accompanied by the Original Definitions of Era, Period and Epoch Terms. Department of the Interior, United States Geological Survey, 1925.