Gaya APA
Covey, Stephen R. (1990).
Principle-centered leadership .
New York:
Simon and Schuster.
Gaya Chicago
Covey, Stephen R.
Principle-centered leadership.
New York:
Simon and Schuster,
1990.
Buku.
Gaya MLA
Covey, Stephen R.
Principle-centered leadership.
New York:
Simon and Schuster,
1990.
Buku.
Gaya Turabian
Covey, Stephen R.
Principle-centered leadership.
New York:
Simon and Schuster,
1990.
Buku.