APA (7th ed.) Citation

Geffs, M. L. (1938). Under ten flags: A history of Weld county, Colorado. [publisher not identified].

Chicago Style (17th ed.) Citation

Geffs, Mary L. Under Ten Flags: A History of Weld County, Colorado. Greeley, Colo.: [publisher not identified], 1938.

MLA (9th ed.) Citation

Geffs, Mary L. Under Ten Flags: A History of Weld County, Colorado. [publisher not identified], 1938.