Moore, W.G.
London : Penguin Books, 1984,
Buku Referensi
Mayhew, Susan
Oxford University Press, 1992
Buku Referensi
edited by Stephen Goddard
Barnes & Noble Books , 1983
Buku Referensi
Painter, Richard W.
Pluto Press, 1993
Buku Teks
Shugar, Gershon J.
McGraw-Hill, 1990
Buku Referensi