Twomey, David P.
South-Western Publishing Company, 1986
Buku Teks
Carvan, John
LBC Information Service, 1997
Buku Teks
Mason, Peter, author
Routledge, 1998
Buku Teks
Barnes, A. James, author
Learning Systems, 1981
Buku Teks
edited by Mark Howard, Roger Masefield ; assistant editor, Jason Chuah
Nexis Butterworths, 2006
Buku Teks