APA Citation

Yard, R. S., & Story, I. F. (1931). The national parks portfolio (Sixth Edition.). Washington: United States Government Printing Office.

Chicago Style Citation

Yard, Robert Sterling., and Isabelle F. Story. The National Parks Portfolio. Sixth Edition. Washington: United States Government Printing Office, 1931.

MLA Citation

Yard, Robert Sterling., and Isabelle F. Story. The National Parks Portfolio. Sixth Edition. Washington: United States Government Printing Office, 1931.

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