Creighton, Donald, author
Macmillan, 1956
Buku Teks
Price, Roger, author
Routledge, 1997
Buku Teks
Dallin, David J., author
Hollis & Carter, 1951
Buku Teks
edited by William E. Griffith
Lexington Books, 1976
Buku Teks
Coupland, R., author
McMillan, 1935
Buku Teks