The Guilford Press, 2007
Buku Teks
Back, Kurt W.
John Wiley & Sons, 1977
Buku Teks
DeLamater, John D., author
Colorado Westview Press, 2014
Buku Teks
Pines, Ayala, author
McGraw-Hill, 1993
Buku Teks
Baron, Robert A., author
Heights Allyn and Bacon , 1991
Buku Teks