Covey, S. R. (1989). The seven habits of highly effective people: Restoring the character ethic. New York: A Fireside Book.
Dyfyniad Arddull ChicagoCovey, Stephen R. The Seven Habits of Highly Effective People: Restoring the Character Ethic. New York: A Fireside Book, 1989.
Dyfyniad MLACovey, Stephen R. The Seven Habits of Highly Effective People: Restoring the Character Ethic. New York: A Fireside Book, 1989.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.