Campbell, Alastair
Chronicle Books, 2000
Buku Referensi
Houghton Miffiln, 1993
Buku Referensi
Wyatt, Allen L.
McGraw-Hill, 1990
Buku Referensi
Oxford University Press, 1990
Buku Referensi
edited by Sybil P. Parker
New York, McGraw-Hill
Buku Referensi