McLeod, John, author
Open University Press, 2005
Buku Teks
Geldard, Kathyrn, author
Sage, 2002
Buku Teks
Stewart, William, author
How to Books, 1999
Buku Teks
edited by John L. Sheppard
Camberland Collegge of Health, 1984
Buku Teks
Tolan, Janet, author
Sage, 2003
Buku Teks