Covey, S. (1992). The seven habits of highly effective people. Simon & Schuster.
Chicago (17e ed.) BronvermeldingCovey, Stephen. The Seven Habits of Highly Effective People. London: Simon & Schuster, 1992.
MLA (9e ed.) BronvermeldingCovey, Stephen. The Seven Habits of Highly Effective People. Simon & Schuster, 1992.
Let op: Deze citaties zijn niet altijd 100% accuraat.