Dyfyniad APA

YORKEY RICHARD. (1981). REPLY REQUESTED 30 LETTERS OF ADVICE. ADDISON-WESLEY.

Dyfyniad Arddull Chicago

YORKEY RICHARD. REPLY REQUESTED 30 LETTERS OF ADVICE. NEW YORK: ADDISON-WESLEY, 1981.

Dyfyniad MLA

YORKEY RICHARD. REPLY REQUESTED 30 LETTERS OF ADVICE. ADDISON-WESLEY, 1981.

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