Dyfyniad APA

Powell. Retention and Resistance. Utah State University Press.

Dyfyniad Arddull Chicago

Powell. Retention and Resistance. Utah State University Press.

Dyfyniad MLA

Powell. Retention and Resistance. Utah State University Press.

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