Παραπομπή APA

Covey, S. R. (2004). The 7 habits of highly effective people. Pocket books.

Παραπομπή Chicago Style

Covey, Stephan R. The 7 Habits of Highly Effective People. London: Pocket books, 2004.

Παραπομπή MLA

Covey, Stephan R. The 7 Habits of Highly Effective People. Pocket books, 2004.