APA (7th ed.) Citation

Hall, C., Taylor, H., & Harding, R. (1994). Gemstones. Dorling Kindersley.

Chicago Style (17th ed.) Citation

Hall, Cally, Harry Taylor, and Roger Harding. Gemstones. London: Dorling Kindersley, 1994.

MLA (8th ed.) Citation

Hall, Cally, et al. Gemstones. Dorling Kindersley, 1994.