Rees, Nigel, author
Cassell Publishers, 1995
Buku Referensi
Schwartz, Robert J., author
Crowell , 1955
Buku Referensi
Oxford University Press, 1996
Buku Referensi
Smith, William George, compiler
Clarendon Press, 1952
Buku Referensi
McAlpin, Janet, author
England: Longman Group, 1988,
Buku Referensi