Citazione Stile APA (7a Edizione)

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

Citazione stile Chigago Style (17a edizione)

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

Citatione MLA (9a ed.)

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