edited by Terry Hanson
Facet Publishing, 2005
Buku Teks
edited by Gillian M. McCombs
The Haworth Press, 1991
Buku Teks
Ball, David, author
Facet Publishing, 2005
Buku Teks
Reynolds, Amanda, author
Open universtity press , 2000
Buku Teks
edited by Allan McNaught
Chapman and Hall , 1991
Buku Teks