APA (7th ed.) Citation

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

Chicago Style (17th ed.) Citation

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

MLA (8th ed.) Citation

Princeton Language Institute, et al. 10 Days to a Sharper Memory. Warner Books, 2001.