Gilbert, Wilfred C.
The Library of Congress, 1952
Buku Teks
Palmer, Vance
Longman Cheshire, 1981
Buku Teks SO
edited by W. Lee Baldwin and W. David Maxwell
Lexington Books, 1975
Buku Teks SO
McDonnell, Timothy L.
Loyola University Press, 1957
Buku Teks SO
Conboy, Ken
Equinox Pub., 2004
Buku Teks