Bellinger, William Kenneth
Routledge, 2007
Buku Teks SO
Gohagan, John Kenneth
McGraw-Hill, 1980
Buku Teks
by Peter Knoepfel ... [and others]
Policy Press, 2007
Buku Teks SO
Kraft, Michael E.
SAGE, 2015
Buku Teks
edited by Wil A.H. Thissen and Warren E. Walker
Springer, 2013
Buku Teks SO