Here are links from the video:

https://www.lifeextension.com/magazine/2009/12/are-you-getting-optimal-flu-prevention

https://www.lifeextension.com/magazine/2015/11/the-link-between-vitamin-c-and-optimal-immunity

https://www.lifeextension.com/magazine/2020/1/how-to-use-zinc-lozenges https://naturalfactors.com/en-us/product/vitamin-d3-en-us/

https://www.americanhealthus.com/Products/Immune%20Support/Ester-C%C2%AE

https://www.lifeextension.com/vitamins-supplements/item01961/enhanced-zinc-lozenges