APA استشهاد

Covey, S. R. (1999). Principle-centered leadership. Simon & Schuster.

استشهاد بنمط شيكاغو

Covey, Stephen R. Principle-centered Leadership. London: Simon & Schuster, 1999.

MLA استشهاد

Covey, Stephen R. Principle-centered Leadership. Simon & Schuster, 1999.