APA (7th ed.) Citation

Mercola, J. (2021). Upgrade your immunity with herbs: Herbal tonics, broths, brews, and elixirs to supercharge your immune system.

Chicago Style (17th ed.) Citation

Mercola, Joseph. Upgrade Your Immunity with Herbs: Herbal Tonics, Broths, Brews, and Elixirs to Supercharge Your Immune System. 2021.

MLA (8th ed.) Citation

Mercola, Joseph. Upgrade Your Immunity with Herbs: Herbal Tonics, Broths, Brews, and Elixirs to Supercharge Your Immune System. 2021.

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