Dyfyniad APA

(1921). University of California publications. University of California Press.

Dyfyniad Arddull Chicago

University of California Publications. Berkeley: University of California Press, 1921.

Dyfyniad MLA

University of California Publications. University of California Press, 1921.

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