Ford, Donald H.
John Wiley & Sons, 1998
Buku Teks
Claringbull, Norman, author
Learning Matters, 2011
Buku Teks
Bager-Charleson, Sofie, author
Learning Matters, 2011
Buku Teks
McLeod, John, author
Sage Publications, 2002
Buku Teks
Joyce, Phil, author
Sage Publications , 2004
Buku Teks