Kirst-Ashman, Karen Kay, author
Thomson , 2006
Buku Teks
Levy, Robert M.
Southern Illinois University Press, 1996
Buku Teks
Peter Aggleton, Jane Hurry, Ian Warwick, editor
John Wiley & Sons, 2000
Buku Teks
Artikel Jurnal
Cowan, David, author
Cambridge University Press, 2011
Buku Teks