Elkins, Richard E., author
University of Hawaii Press, 1968
Buku Referensi
London: Tiger Books International, 1994,
Buku Referensi
Guandola, M.H.
Merriam & Webster, INC, 1989
Buku Teks
1976
Buku Teks
Corsini, Raymond J., author
Brunner-Routledge, 2002
Buku Teks