Rosenberg, Morris, author
Basic Books, 1968
Buku Teks
Moser, Claus A., author
Heineman Education Books, 1979
Buku Teks
John Wiley & Sons, 2004
Buku Teks
Fink, Arlene, author
Thousand Oaks : SAGE PUBLIKATION, 2003,
Buku Referensi
Fink, Arlene, author
Thousand Oaks : SAGE PUBLIKATION, 2003,
Buku Referensi