Dyfyniad APA

Covey, S. R. (1999). Seven habits of highly effective people (1st.). Pocket books.

Dyfyniad Arddull Chicago

Covey, Stephen R. Seven Habits of Highly Effective People. 1st. London: Pocket books, 1999.

Dyfyniad MLA

Covey, Stephen R. Seven Habits of Highly Effective People. 1st. Pocket books, 1999.

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