Bloom, Allan
Simon and Schuster, 1987
Buku Teks
Nye, Russel B.
Michigan State University Press, 1959
Buku Teks
Johns Hopkins University Press, 1979
Buku Teks
Peck, David W.
Greenwood Press , 1961
Buku Teks
Curti, Merle
Harper & Brothers, 1951
Buku Teks