APA (7th ed.) Citation

Philip Lief Group, Princeton Language Institute, & Robert, R. (2001). 10 days to a sharper memory. Warner Books.

Chicago Style (17th ed.) Citation

Philip Lief Group, Princeton Language Institute, and Russell Robert. 10 Days to a Sharper Memory. New York: Warner Books, 2001.

MLA (9th ed.) Citation

Philip Lief Group, et al. 10 Days to a Sharper Memory. Warner Books, 2001.