APA

Butterfield W. H., . (1941). The business letter in modern form. New York: Prentice-Hall, inc.

Chicago

Butterfield William Henry, . 1941. The business letter in modern form. New York: Prentice-Hall, inc.

Harvard

Butterfield W. H., . (1941). The business letter in modern form. New York: Prentice-Hall, inc.

MLA

Butterfield William Henry, . The business letter in modern form. New York: Prentice-Hall, inc. 1941.