APA

Covey Stephen R,, . (1992). The seven habits of highly effective people : Powerful lessons in personal change. London: Simon & Schuster.

Chicago

Covey Stephen R,, . 1992. The seven habits of highly effective people : Powerful lessons in personal change. London: Simon & Schuster.

Harvard

Covey Stephen R,, . (1992). The seven habits of highly effective people : Powerful lessons in personal change. London: Simon & Schuster.

MLA

Covey Stephen R,, . The seven habits of highly effective people : Powerful lessons in personal change. London: Simon & Schuster. 1992.