Gaya APA
Covey, Stephen R.. (1991).
Principle-centered leadership .
London:
Simon & Schuster.
Gaya Chicago
Covey, Stephen R..
Principle-centered leadership.
London:
Simon & Schuster,
1991.
Text.
Gaya MLA
Covey, Stephen R..
Principle-centered leadership.
London:
Simon & Schuster,
1991.
Text.
Gaya Turabian
Covey, Stephen R..
Principle-centered leadership.
London:
Simon & Schuster,
1991.
Print.