Murphy, Robert F.
Prentice-Hall, 1986
Buku Teks
Hammond, Peter
Macmillan, 1978
Buku Teks
Rapport, Nigel
Routledge, 2000
Buku Teks
Pennsylvania : University of Pittsburgh Press
Majalah, Jurnal, Buletin
Kottak, Conrad Phillip
McGraw-Hill , 1991
Buku Teks