Covey, S, R.(1990).7 Habits of Highly Effective People, The : Powerful Lessons in Personal Change (First Edition).New York, USA:Simon & Schuster.
Gaya MLA
Covey, Stephen, R.."7 Habits of Highly Effective People, The : Powerful Lessons in Personal Change".First EditionNew York, USA:Simon & Schuster,1990.Academic.