APA ציטוט

Covey, S. R. (1991). Principle centered leadership. New York: A Fireside.

Trích dẫn kiểu Chicago

Covey, Stephen R. Principle Centered Leadership. New York: A Fireside, 1991.

ציטוט MLA

Covey, Stephen R. Principle Centered Leadership. New York: A Fireside, 1991.