1. Braunig B, Dorn M, Limburg E, et al. Echinacea purpurea radix for strengthening the immune response in flu-like infections. Z Phytother 1992;13:7-13 [in German].
2. Beuscher N, Kopanski L. Stimulation of immunity by the contents of Baptisia tinctoria. Planta Med 1985;5:381-4.
3. Zakay-Rones Z, Varsano N, Zlotnik M, et al. Inhibition of several strains of influenza virus in vitro and reduction of symptoms by an elderberry extract (Sambucus nigra L.) during an outbreak of influenza B Panama. J Alt Compl Med 1995;1:361-9.
4. Nantz MP, Rowe CA, Muller CE, et al. Supplementation with aged garlic extract improves both NK and γδ-T cell function and reduces the severity of cold and flu symptoms: a randomized, double-blind, placebo-controlled nutrition intervention. Clin Nutr 2012;31:337-44.
5. Yamada H, Takuma N, Daimon T, Hara Y. Gargling with tea catechin extracts for the prevention of influenza infection in elderly nursing home residents: a prospective clinical study. J Altern Complement Med 2006;12:669-72.
6. Matsumoto K, Yamada H, Takuma N, et al. Effects of green tea catechins and theanine on preventing influenza infection among healthcare workers: a randomized controlled trial. BMC Complement Altern Med 2011;11:15.
7. Renker K, Wegner S. Vitamin C-Prophylaxe in der Volkswertf Stralsund. Deutsche Gesundheitswesen 1954;9:702-6.
8. Klenner FR. The treatment of poliomyelitis and other virus diseases with vitamin C. South Med Surg 1949;111:210-4.
9. Pauling L. Vitamin C, the Common Cold and the Flu. San Francisco: W. H. Freeman & Company, 1976 [review].
10. Aloia JF, Li-Ng M. Re: epidemic influenza and vitamin D. Epidemiol Infect 2007;135:1095-6.
11. Scaglione F, Cattaneo G, Alessandria M, Cogo R. Efficacy and safety of the standardized ginseng extract G 115 for potentiating vaccination against common cold and/or influenza syndrome. Drugs Exp Clin Res 1996;22:65-72.
12. Woerdenbag HJ, Bos R, Hendriks H. Eupatorium perfoliatum L—the boneset. Z Phytother 1992;13:134-9 [review].
13. Beuscher N, Kopanski L. Stimulation of immunity by the contents of Baptisia tinctoria. Planta Med 1985;5:381-4.
14. Scaglione F, Cattaneo G, Alessandria M, Cogo R. Efficacy and safety of the standardized ginseng extract G 115 for potentiating vaccination against common cold and/or influenza syndrome. Drugs Exp Clin Res 1996;22:65-72.
15. Beuscher N, Kopanski L. Stimulation of immunity by the contents of Baptisia tinctoria. Planta Med 1985;5:381-4.
16. Beuscher N, Kopanski L. Stimulation of immunity by the contents of Baptisia tinctoria. Planta Med 1985;5:381-4.
17. Beuscher N, Kopanski L. Stimulation of immunity by the contents of Baptisia tinctoria. Planta Med 1985;5:381-4.
18. Clover RD, Abell T, Becker LA, et al. Family functioning and stress as predictors of influenza B infection. J Fam Pract 1989;28:535-9.