Derlega, Valerian J.
Scott Foresman , 1981
Buku Teks
Covey, Sean
A Fireside Book, 2004
Buku Teks
Covey, Sean
[publisher not identified], [date of publication no identified]
Buku Teks
DuBrin, Andrew J.
Reston Publishing Company, 1983
Buku Teks
Covey, Stephen R.
Simon & Schuster , 1990
Buku Teks