Schapiro, J. Salwyn
McGraw-Hill Book Company, Inc., 1950
Buku Teks
Snyder, Houis L.
Princeton University Press, 1964
Buku Teks
Routledge, 1992
Buku Teks
Mende, Tibor
The Noonday Press, 1953
Buku Teks
Kegley, Charles W. (Charles William), Jr., author
Wardsworth, 2010
Buku Teks