(1) Schapowal, Andreas, et al. “Echinacea/Sage or Chlorhexidine/Lidocaine for Treating Acute Sore Throats: A Randomized Double-Blind Trial.”European Journal of Medical Research, flight. 14, no. 9, September 2009, p. 406‑12.PubMed, https://doi.org/10.1186/2047-783x-14-9-406.
(2) Salehi, Bahare, et al. “Thymol, Thyme, and Other Plant Sources: Health and Potential Uses.”Phytotherapy Research: PTR, flight. 32, no. 9, September 2018, p. 1688‑706.PubMed, https://doi.org/10.1002/ptr.6109.
(3) Kowalczyk, Adam, et al. “Thymol and Thyme Essential Oil—New Insights into Selected Therapeutic Applications.” Molecules, vol. 25, no. 18, September 2020, p. 4125. PubMed Central, https://doi.org/10.3390/molecules25184125
(4) Załuski, Daniel, et al. “Phytochemical Content and Pharma-Nutrition Study on Eleutherococcus senticosus Fruits Intractum”.Oxidative Medicine and Cellular Longevity, flight. 2016, 2016, p. 9270691.PubMed Central, https://doi.org/10.1155/2016/9270691.
(5) Aranow, Cynthia. “Vitamin D and the Immune System”. Journal of investigative medicine: the official publication of the American Federation for Clinical Research, vol. 59, no. 6, August 2011, p. 881‑86. PubMed Central, https://doi.org/10.231/JIM.0b013e31821b8755.
(6) Prietl, Barbara, et al. “Vitamin D and Immune Function.” Nutrients, vol. 5, no. 7, July 2013, pp. 2502-21. PubMed, https://doi.org/10.3390/nu5072502.
(7) Batista, Kamila S., et al. “The role of vitamin B12 in viral infections: a comprehensive review of its relationship with the muscle–gut–brain axis and implications for SARS-CoV-2 infection”. Nutrition Reviews, November 2021, p. nuab092. PubMed Central, https://doi.org/10.1093/nutrit/nuab092.