Bernard, Miriam, author
Open University Press , 2000
Buku Teks
Editor: Souzy Dracopoulou
Routledge, 1998
Buku Teks
Charns, Martin P., author
Prentice-Hall, 1983
Buku Teks
Brown, Montague, author
Aspen Publication, 1982
Buku Teks
McLean, Robert A., author
Delmar, 1997
Buku Teks