Παραπομπή APA

Covey, S. R. (1989). The 7 habits of highly effective people: Restoring the character ethic. Pocket books.

Παραπομπή Chicago Style

Covey, Stephen R. The 7 Habits of Highly Effective People: Restoring the Character Ethic. London: Pocket books, 1989.

Παραπομπή MLA

Covey, Stephen R. The 7 Habits of Highly Effective People: Restoring the Character Ethic. Pocket books, 1989.