Παραπομπή σε μορφή APA (7η εκδ.)

Keiter, R. B. (2013). To Conserve Unimpaired: The Evolution of the National Park Idea. Island Press/Center for Resource Economics : Imprint: Island Press.

Παραπομπή σε μορφή Chicago (17η εκδ.)

Keiter, Robert B. To Conserve Unimpaired: The Evolution of the National Park Idea. Washington, DC: Island Press/Center for Resource Economics : Imprint: Island Press, 2013.

Παραπομπή σε μορφή MLA (8th εκδ.)

Keiter, Robert B. To Conserve Unimpaired: The Evolution of the National Park Idea. Island Press/Center for Resource Economics : Imprint: Island Press, 2013.