Dyfyniad APA

Barkley, A., & Barkley, P. W. (2013). Principles of agricultural economics. Routledge.

Dyfyniad Arddull Chicago

Barkley, Andrew, and Paul W. Barkley. Principles of Agricultural Economics. London, New York: Routledge, 2013.

Dyfyniad MLA

Barkley, Andrew, and Paul W. Barkley. Principles of Agricultural Economics. Routledge, 2013.

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