Charles Webster
Open University Press, 2001
Buku Teks
edited by Basiro Davey, Alastair Gray, Clive Seale
Open University Press, 2001
Buku Teks
Hitchcock, Janice E., author
Delmar, 1999
Buku Teks
Walters, Vivienne J., author
Croom Helm, 1980
Buku Teks
Lundy, Karen Saucier, author
Jones and Bartlett , 2009
Buku Teks