Keyssar, Helene
Macmillan Press , 1972
Buku Teks
Turner, Paul, author
Clarendon Press, 1990
Buku Referensi
Bull, John, author
Macmillan, 1991
Buku Teks
Hirst, David L., author
Macmillan, 1985
Buku Teks
edited by Arthur F. Kinney and Thomas Warren Hopper
Wiley/Balckwell, 2017
Buku Teks