Downer, Alan, author
University of Minnesota Press, 1961
Buku Teks
Berkowitz, Gerald M., author
Longman, 1994
Buku Teks
Gagey, Edmond M., author
Columbia University Press, 1948
Buku Teks
Bonner, Thomas Neville, author
Prentice-Hall, 1963
Buku Teks
Divine, Robert A., author
Alfred A. Knopf, 1985
Buku Teks