Covey, S. R. (1999). Seven habits of highly effective people (1st.). Pocket books.
Chicago Edition CitationCovey, Stephen R. Seven Habits of Highly Effective People. 1st. London: Pocket books, 1999.
Cita MLACovey, Stephen R. Seven Habits of Highly Effective People. 1st. Pocket books, 1999.
Atenció: Aquestes cites poden no estar 100% correctes.