Hitch, Charles J.
University of California Press, 1965
Buku Teks
Van de Ven, Andrew H.
Kent State University Press, 1974
Buku Teks
Raven press, 1983
Buku Teks
Hamburg, Morris
Harcourt Brace Jovanovich, Pub., 1991
Buku Teks
Zimmerman, Jerold L., 1947-
McGraw-Hill, 1997
Buku Teks