Gaya APA

Covey, Stephen R.. (1991). Principle centred leadership . New York: Simon & Schuster.

Gaya Chicago

Covey, Stephen R.. Principle centred leadership. New York: Simon & Schuster, 1991. Text.

Gaya MLA

Covey, Stephen R.. Principle centred leadership. New York: Simon & Schuster, 1991. Text.

Gaya Turabian

Covey, Stephen R.. Principle centred leadership. New York: Simon & Schuster, 1991. Print.