Covey, S. R. (1991). Principle centered leadership. New York: A Fireside.
शिकागो स्टाइल उद्धरणCovey, Stephen R. Principle Centered Leadership. New York: A Fireside, 1991.
एमएलए उद्धरणCovey, Stephen R. Principle Centered Leadership. New York: A Fireside, 1991.
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