Pergamon Press , 1979
Buku Teks
Lind, Douglas A., author
Salemba Empat, 2008
Buku Teks
Aron, Arthur, author
Prentice-Hall, 1997
Buku Teks
Abrami, Philip C., author
Allyn and Bacon, 2001
Buku Teks
David Collier, John Gerring, editor
Routledge, 2009
Buku Teks