Παραπομπή APA

Covey, S. R. (1990). Seven Habits of Highly Offective People: Restoring the Charactor Ethic. Fireside.

Παραπομπή Chicago Style

Covey, Stephen R. Seven Habits of Highly Offective People: Restoring the Charactor Ethic. New York: Fireside, 1990.

Παραπομπή MLA

Covey, Stephen R. Seven Habits of Highly Offective People: Restoring the Charactor Ethic. Fireside, 1990.