APA (7th ed.) Citation

Pennell, F. W. (1920). Scrophulariaceae of central Rocky Mountain States. U.S. Government Printing Office.

Chicago Style (17th ed.) Citation

Pennell, Francis W. Scrophulariaceae of Central Rocky Mountain States. [Place of publication not identified]: U.S. Government Printing Office, 1920.

MLA (9th ed.) Citation

Pennell, Francis W. Scrophulariaceae of Central Rocky Mountain States. U.S. Government Printing Office, 1920.

Warning: These citations may not always be 100% accurate.