APA (7th ed.) Citation

Funk, W., & Lewis. (1970). 30 days to a more powerful vacobulary. Pocket Books.

Chicago Style (17th ed.) Citation

Funk, Wilfred, and Lewis. 30 Days to a More Powerful Vacobulary. New York: Pocket Books, 1970.

MLA (8th ed.) Citation

Funk, Wilfred, and Lewis. 30 Days to a More Powerful Vacobulary. Pocket Books, 1970.

Warning: These citations may not always be 100% accurate.