Dyfyniad APA

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

Dyfyniad Arddull Chicago

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

Dyfyniad MLA

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

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.