Campbell, George L., author
Routledge, 1995
Buku Referensi
edited by Bernard Comrie
Oxford University Press, 1987
Buku Teks
Klett, 2006
Buku Referensi
C. S. Hammond and Company
C.S. Hammond & Co., [date of publication not identified]
Buku Teks
McEvery, Colin, author
Facts On File, 1979
Buku Referensi