Covey, S. R. (1991). Principle-centered leadershipages (First edition.). A Fireside Book.
Chicagoスタイル(17版)引用形式Covey, Stephen R. Principle-centered Leadershipages. First edition. New York: A Fireside Book, 1991.
MLA(9版)引用形式Covey, Stephen R. Principle-centered Leadershipages. First edition. A Fireside Book, 1991.
警告: この引用は必ずしも正確ではありません.