Covey, S. (1992). The seven habits of highly effective people. Simon & Schuster.
Citazione stile Chigago Style (17a edizione)Covey, Stephen. The Seven Habits of Highly Effective People. London: Simon & Schuster, 1992.
Citatione MLA (9a ed.)Covey, Stephen. The Seven Habits of Highly Effective People. Simon & Schuster, 1992.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.