APA

Funk W., Norman L., . (1946). 30 days a more powerful vocabulary. New York: Frank W.

Chicago

Funk Wilfred, Norman Lewis, . 1946. 30 days a more powerful vocabulary. New York: Frank W.

Harvard

Funk W., Norman L., . (1946). 30 days a more powerful vocabulary. New York: Frank W.

MLA

Funk Wilfred, Norman Lewis, . 30 days a more powerful vocabulary. New York: Frank W. 1946.