Covey, S. R. (1989). The seven habits of highly effective people: Restoring the character ethic. Simon and Schuster.
Chicago-Zitierstil (17. Ausg.)Covey, Stephen R. The Seven Habits of Highly Effective People: Restoring the Character Ethic. New York: Simon and Schuster, 1989.
MLA-Zitierstil (8. Ausg.)Covey, Stephen R. The Seven Habits of Highly Effective People: Restoring the Character Ethic. Simon and Schuster, 1989.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.