Creswell, John W., author
Sage, 1994
Buku Teks
Rosnow, Ralph L., author
Prentice-Hall, 1996
Buku Teks
New jersey, 2004
Buku Teks
Neuman, William Lawrence, 1950-, author
Allyn and Bacon, 1994
Buku Teks
Cozby, Paul C., author
McGraw-Hill, 2003
Buku Teks