Dyfyniad APA

(1978). Professional and non-professional roels [2]. Open University.

Dyfyniad Arddull Chicago

Professional and Non-professional Roels [2]. Walton Hall: Open University, 1978.

Dyfyniad MLA

Professional and Non-professional Roels [2]. Open University, 1978.

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