Powell, Robert G., author
Lawrence Erlbaum Associates, 2004
Buku Teks
Schneekloth, Lynda H., editor
John Wiley & Sons, 1995
Buku Teks
Powell, Robert
Cambridge University Press, 1990
Buku Teks
Wetzel, Robert G.
Saunders College Publishing, 1983
Buku Teks
Santrock, John W., author
McGraw-Hill, 2006
Buku Teks