Freeman, Stanley K.
John Wiley & Sons, 1974
Buku Teks
edited by M.J. Toswell and E.M. Tyler
Routledge, 1996
Buku Referensi
Eitzen, D. Stanley
Allyn and Bacon, 1989
Buku Teks
Adcock, Sir Frank
Thames and Hudson, 1975
Buku Teks
Kissinger, Henry, 1923-
Schuter, 1994
Buku Teks