APA aipamena

Butterfield, W. H. (1951). Effective personal letters (2nd edition.). Prentice-Hall.

Chicago Style aipamena

Butterfield, William Henry. Effective Personal Letters. 2nd edition. New York: Prentice-Hall, 1951.

MLA aipamena

Butterfield, William Henry. Effective Personal Letters. 2nd edition. Prentice-Hall, 1951.