APA
Covey S. R., . (1997). The 7 habits of highly effective people. Pocket Books, London: .
Chicago
Covey Stephen R, . 1997. The 7 habits of highly effective people. Pocket Books, London: .
Harvard
Covey S. R., . (1997). The 7 habits of highly effective people. Pocket Books, London: .
MLA
Covey Stephen R, . The 7 habits of highly effective people. Pocket Books, London: . 1997.