Covey, S. (1992). The seven habits of highly effective people. Simon & Schuster.
Chicago-viite (17. p.)Covey, Stephen. The Seven Habits of Highly Effective People. London: Simon & Schuster, 1992.
MLA-viite (9. p.)Covey, Stephen. The Seven Habits of Highly Effective People. Simon & Schuster, 1992.
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