APA (7th ed.) Citation

Johnson, R. L., Foster, S., & Weil, A. (2010). National Geographic guide to medicinal herbs. National Geographic Society.

Chicago Style (17th ed.) Citation

Johnson, Rebecca L., Steven Foster, and Andrew Weil. National Geographic Guide to Medicinal Herbs. Washington: National Geographic Society, 2010.

MLA (9th ed.) Citation

Johnson, Rebecca L., et al. National Geographic Guide to Medicinal Herbs. National Geographic Society, 2010.