editor in chief, Charles A. Ford
Encyclopedia Britannica Educational Corporation, 1969
Buku Referensi
Porter, Philip
Haynes, 1995
Buku Referensi
Singh, Khuswant
Oxford University Press, 2006
Buku Teks
edited by Geoffrey Parker
Cambridge University Press, 1995
Buku Referensi
editor, John Prest
Oxford University Press, 1993
Buku Referensi