APA

Covey S. R., . (1989). The seven habits of highly effective people. New York: Simon & Schuster.

Chicago

Covey Stephen R, . 1989. The seven habits of highly effective people. New York: Simon & Schuster.

Harvard

Covey S. R., . (1989). The seven habits of highly effective people. New York: Simon & Schuster.

MLA

Covey Stephen R, . The seven habits of highly effective people. New York: Simon & Schuster. 1989.