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