Bartlett, Ruhl
Hill and Wang, 1963
Buku Teks
Perkins, Dexter
Harvard University Press, 1954
Buku Teks
Nathan, James A
Little, Brown, 1983
Buku Teks
Stanley, Timothy W., author
Westview Press, 1982
Buku Teks
Vernon, Raymond, author
Free Press, 1989
Buku Teks