edited by David Popenoe
Rutgers University Press, 1969
Buku Teks
Shostak, Arthur B.
Macmillan Publishing Company, 1974
Buku Teks
Warner, W. Lloyd, author
Yale University Press, 1955
Buku Teks
Warner, W. Lloyd, author
Yale University Press, 1941
Buku Teks
May, John D.
Duxbury Press, 1972
Buku Teks