Butterfiel, W. (1964). Effective personal letters (2nd rev.). Prentice Hall.
Chicagoスタイル(17版)引用形式Butterfiel, W. Effective Personal Letters. 2nd rev. Englewood Cliffs: Prentice Hall, 1964.
MLA(9版)引用形式Butterfiel, W. Effective Personal Letters. 2nd rev. Prentice Hall, 1964.
警告: この引用は必ずしも正確ではありません.