Covey, S. R. (1989). 7 habits of highly effective people.
Chicago Edition CitationCovey, Stephen R. 7 Habits of Highly Effective People. Pocket Books, London, 1989.
Cita MLACovey, Stephen R. 7 Habits of Highly Effective People. 1989.
Atenció: Aquestes cites poden no estar 100% correctes.