Sage Publications, Inc, 2005
Majalah, Jurnal, Buletin
Noble, David F.
Oxford Univ. Press , 1977
Buku Teks
Arnold, Thurman Wesley, author
Blue Ribbon Books, 1937
Buku Klasik
Martin, Kingsley
New York University Press, 1954
Buku Teks
Tigar, Michael E.
Monthly Riview Press, 1977
Buku Teks