APA (7th ed.) Citation

Funk, W. (1942). 30 days to a more powerful vocabulary. Pocket Books.

Chicago Style (17th ed.) Citation

Funk, Wilfred. 30 Days to a More Powerful Vocabulary. New York: Pocket Books, 1942.

MLA (9th ed.) Citation

Funk, Wilfred. 30 Days to a More Powerful Vocabulary. Pocket Books, 1942.