Covey, S. R. The 7 habits of highly effective people: Restoring the character ethic (Revised edition.).
Chicago-referens (17:e uppl.)Covey, Stephen R. The 7 Habits of Highly Effective People: Restoring the Character Ethic. Revised edition.
MLA-referens (8:e uppl.)Covey, Stephen R. The 7 Habits of Highly Effective People: Restoring the Character Ethic. Revised edition.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.