Cita APA (7th ed.)

Butterfield, W. H. (1956). Common sense in letter writing: Seven steps to better results by mail. Prentice-Hall.

Cita Chicago (17th ed.)

Butterfield, William H. Common Sense in Letter Writing: Seven Steps to Better Results by Mail. Englewood Cliffs, N.J: Prentice-Hall, 1956.

Cita MLA (9th ed.)

Butterfield, William H. Common Sense in Letter Writing: Seven Steps to Better Results by Mail. Prentice-Hall, 1956.