Dyfyniad APA

Schaie, K. W., & Willis, S. L. (1996). Adult development and aging (4th ed.). Harper Collins College.

Dyfyniad Arddull Chicago

Schaie, K. Warner, and Sherry L. Willis. Adult Development and Aging. 4th ed. New York: Harper Collins College, 1996.

Dyfyniad MLA

Schaie, K. Warner, and Sherry L. Willis. Adult Development and Aging. 4th ed. Harper Collins College, 1996.

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