Citazione Stile APA (7a Edizione)

United States National Park Service. (1965). Outdoor recreation in the National Capital Region. National Capital Open Space Program.

Citazione stile Chigago Style (17a edizione)

United States National Park Service. Outdoor Recreation in the National Capital Region. Washington, D.C: National Capital Open Space Program, 1965.

Citatione MLA (9a ed.)

United States National Park Service. Outdoor Recreation in the National Capital Region. National Capital Open Space Program, 1965.