edited by Robert L. Chapman
Collins, 1989
Buku Referensi
Chapman, Robert L., author
London Pan Books 1988
Buku Referensi
Lutz, William D., author
Cambridge University Press, 1994
Buku Referensi
N. A. L. Signet Books,
Buku Referensi
Burton, William.
Simon & Schuster Macmillan, 1992
Buku Teks