Παραπομπή APA

Stephen R. Covey. (2004). The 8th habit: From effectiveness to greatness. Free Press.

Παραπομπή Chicago Style

Stephen R. Covey. The 8th Habit: From Effectiveness to Greatness. New York: Free Press, 2004.

Παραπομπή MLA

Stephen R. Covey. The 8th Habit: From Effectiveness to Greatness. Free Press, 2004.