edited by Angela Partington
Oxford University Press, 1993
Buku Referensi
Eigen, Lewis D., author
Macmillan Publishing Company, 1993
Buku Referensi
A Norman Jeffares, Martin Gray, editor
HarperCollinPublisher, 1995
Buku Referensi
Cohen, J.M. (John Michael), 1903-1989, author
Penguin Books, 1971
Buku Referensi
edited by X.J. Kennedy
Little, Brown, 1973
Buku Teks