APA (7th ed.) Citation

Colver, G., Evans, M., & Tripp, P. (1990). Your skin. Harrap Publishing.

Chicago Style (17th ed.) Citation

Colver, Graham, Mark Evans, and Penny Tripp. Your Skin. Kent: Harrap Publishing, 1990.

MLA (9th ed.) Citation

Colver, Graham, et al. Your Skin. Harrap Publishing, 1990.