Covey, S. R. (2002). First Things First. Pocket Books Ltd.
Cita Chicago (17th ed.)Covey, Stephen R. First Things First. London: Pocket Books Ltd, 2002.
Cita MLA (9th ed.)Covey, Stephen R. First Things First. Pocket Books Ltd, 2002.
Atenció: Aquestes cites poden no estar 100% correctes.