Heady, Ferrel
Marcel Dekker, 1991
Buku Teks
Barzelay, Michael, author
University of California Press, 2001
Buku Teks
Williams, J. D., author
Little, Brown and Co., 1980
Buku Teks
United Nations, 2007
Buku Teks
Edited by Robert F. Durant, Jennifer R.S. Durant
CRC Press, 2013
Buku Teks