APA (7e ed.) Bronvermelding

Orr, D. W. (2011). Hope is an imperative: The essential David Orr. Island Press.

Chicago (17e ed.) Bronvermelding

Orr, David W. Hope Is an Imperative: The Essential David Orr. Washington, DC: Island Press, 2011.

MLA (9e ed.) Bronvermelding

Orr, David W. Hope Is an Imperative: The Essential David Orr. Island Press, 2011.