Walford, A. J. Guide to Reference Material (3rd ed.). The Library Association.
Dyfyniad Arddull ChicagoWalford, A J. Guide to Reference Material. 3rd ed. London: The Library Association.
Dyfyniad MLAWalford, A J. Guide to Reference Material. 3rd ed. The Library Association.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.