Mason, Philip, author
Oxford University Press, 1970
Buku Teks
Dunn, L.C., author
UNESCO, 1953
Buku Teks
edited by Edgar T. Thompson, Robert E. Park
Duke University Press, 1939
Buku Teks
Gallagher, Winifred
Random House , 1996
Buku Teks
Taylor, Paul C., author
Polity Press, 2013
Buku Teks