Payne, Stanley Le Baron
Princeton University Press, 1951
Buku Teks
Runciman, Lex
Allyn and Bacon, 1999
Buku Teks SO
Browne, M. Neil
Prentice-Hall, 2001
Buku Teks
Keyton, Joann
Mc Graw Hill, 2015
Buku Teks SO
Australia National University , 1985
Buku Teks