Covey, S. R. (1990). Principle centered leadership. Simon & Schuster.
芝加哥风格引文Covey, Stephen R. Principle Centered Leadership. London: Simon & Schuster, 1990.
MLA引文Covey, Stephen R. Principle Centered Leadership. Simon & Schuster, 1990.
警告：这些引文格式不一定是100％准确.