Taylor, F. Sherwood, author
Frederick A. Praeger, 1955
Buku Teks SO
editor in chief, Charles A. Ford
Encyclopedia Britannica Educational Corporation, 1969
Buku Referensi
edited by Jonathan Bate and Russell Jackson
Oxford University Press, 1996
Buku Teks
Wilkes, Peter, author
Peter Wilkes, 1978
Buku Teks
edited by Peter Hunt
Oxford University Press , 1995
Buku Teks