APA (7th ed.) Citation

United States. National Park Service & Yard, R. S. (1925). The National parks portfolio (4th ed.). Govt. Pr. Off..

Chicago Style (17th ed.) Citation

United States. National Park Service and Robert Sterling Yard. The National Parks Portfolio. 4th ed. Washington: Govt. Pr. Off., 1925.

MLA (8th ed.) Citation

United States. National Park Service and Robert Sterling Yard. The National Parks Portfolio. 4th ed. Govt. Pr. Off., 1925.

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