Cita APA (7th ed.)

Covey, S. R. (1991). Principle-centered leadershipages (First edition.). A Fireside Book.

Cita Chicago (17th ed.)

Covey, Stephen R. Principle-centered Leadershipages. First edition. New York: A Fireside Book, 1991.

Cita MLA (9th ed.)

Covey, Stephen R. Principle-centered Leadershipages. First edition. A Fireside Book, 1991.