Covey Stephen R. (2004). 7 Habits of highly effective people. Pocket Books.
Citazione stile Chigago Style (17a edizione)Covey Stephen R. 7 Habits of Highly Effective People. London: Pocket Books, 2004.
Citatione MLA (9a ed.)Covey Stephen R. 7 Habits of Highly Effective People. Pocket Books, 2004.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.