Niven, Neil
Churchill Livingstone , 1994
Buku Teks
Tan, Joseph, author
Jossey-Bass, 2005
Buku Teks
Louis Rubino, Salvador Esparza, Yolanda Reid Chassiakos, editor
Jones & Bartlett Learning, 2014
Buku Teks
Goodman, Michael, author
American Psychiatic Press , 1996
Buku Teks
Goss, Sue, author
HMSO, Department of the Environment, 1994
Buku Referensi