Gordon, Robert Aaron
Berkeley, Cal, University of California Press
Buku Teks
Colombo, Ronald J.
Oxford University Press, 2015
Buku Teks
Hammer, Michael, 1948-2008
Harper Collins, 2003
Buku Teks
Heider, John
PPM, 2006
Buku Teks
Cerami, Charles A.
Prentice-Hall, 1955
Buku Teks