APA (7th ed.) Citation

Zeller, P. K. (1990). Focus on marijuana. Twenty-first Century Books.

Chicago Style (17th ed.) Citation

Zeller, Paula Klevan. Focus on Marijuana. Frederick, MD: Twenty-first Century Books, 1990.

MLA (9th ed.) Citation

Zeller, Paula Klevan. Focus on Marijuana. Twenty-first Century Books, 1990.