by Peter Knoepfel ... [and others]
Policy Press, 2007
Buku Teks SO
edited by Joseph S. Wholey
Jossey-Bass Publishers, 1994
Buku Teks
Dunn, William N.
Gadjah Mada University Press , 2003
Buku Teks SO
Smith, Kevin
Westview Press, Boston, Massachusetts : Credo Reference, 2013
Buku Teks SO
Fischer, Frank
Oxford University Press, 2012
Buku Teks SO