Cita APA

Covey, S. R. (1991). Principle centred leadership (2nd ed.). Pocket Books.

Chicago Edition Citation

Covey, Stephen R. Principle Centred Leadership. 2nd ed. London: Pocket Books, 1991.

Cita MLA

Covey, Stephen R. Principle Centred Leadership. 2nd ed. Pocket Books, 1991.