National Center for Complementary and Integrative Health: "5 Tips: Natural Products for the Flu and Colds: What Does the Science Say?"<br>Harvard Health Publications: "10 Flu Myths."<br>NPR: "Stepping Up Exercise Could Help Beat The Cold Virus," 10 Flu Myths."<br>British Journal of Sports Medicine: "Upper respiratory tract infection is reduced in physically fit and active adults."<br>CDC: "How Flu Spreads," "Common Colds: Protect Yourself and Others."<br>Mayo Clinic: "Can chicken soup cure a cold?"