APA (7th ed.) Citation

Holford, P., & O' Leary. (1999). Improve your digestion. Piatkus.

Chicago Style (17th ed.) Citation

Holford, Patrick, and O' Leary. Improve Your Digestion. London: Piatkus, 1999.

MLA (9th ed.) Citation

Holford, Patrick, and O' Leary. Improve Your Digestion. Piatkus, 1999.

Warning: These citations may not always be 100% accurate.