Wyatt, Allen L.
McGraw-Hill, 1990
Buku Referensi
Anderson, R.G.
Macdonald & Evans, 1982
Buku Referensi
Campbell, Alastair
Chronicle Books, 2000
Buku Referensi
Oxford University Press, 1990
Buku Referensi
edited by George McDaniel
McGraw-Hill, 1994
Buku Referensi