compiled and edited by Justin Wintle
Free Press, 1989
Buku Referensi
edited by Brigadier Peter Young
Hamlyn, 1981
Buku Referensi
Vaux, Kenneth L
Westerview Press, 1992
Buku Teks
Gilpin, Robert, author
Cambridge University Press, 1981
Buku Teks
Garrison, Web
The Lion Press, 2002
Buku Teks