Mogel, Leonard
Collier Books Macmillan Publishing, 1993
Buku Teks
Oxley, Harold
Gunung Mulia, 1993
Buku Teks
Lawrence Erlbaum Associates, Publishers, 2003
Buku Teks
Cutlip, Scott M., author
Prentice Hall International, 2000
Buku Teks
Oemi Abdurrachman
Citra Aditya Bakti, 1995
Buku Teks