Covey, S. R. (2009). The 7 habits of highly effective people.
Cita Chicago Style (17a ed.)Covey, Stephen R. The 7 Habits of Highly Effective People. 2009.
Cita MLA (8a ed.)Covey, Stephen R. The 7 Habits of Highly Effective People. 2009.
Precaución: Estas citas no son 100% exactas.