Covey, S. R. (1999). Seven habits of highly effective people (1st.). Pocket books.
Chicago Style citaatCovey, Stephen R. Seven Habits of Highly Effective People. 1st. London: Pocket books, 1999.
MLA citatieCovey, Stephen R. Seven Habits of Highly Effective People. 1st. Pocket books, 1999.
Let op: Deze citaties zijn niet altijd 100% accuraat.