Durie, Mark
Cinnaminson-U. S. A. : Foris Publications, 1985
Buku Teks
Azar, Betty Schrampfer, 1941-, author
Longman, 2002
Buku Teks
Holschuh, Louis W.
New York St. Martin's Press 1991,
Buku Teks
Phythian, B.A.
London Hodder & Stoughton 1992,
Buku Teks
Buku Teks