GwaltneyJ.M., & HaydenE.G. (Eds.). (2003). Welcome to common cold. Retrieved July 9, 2004, from http://www.commoncold.org
2.
National Institutes of Health (NIH), U.S. Department of Health and Human Services, National Institute of Allergy and Infectious Diseases. (2001). The common cold. Retrieved July 9, 2004, from www.niaid.nih.gov/factsheets/cold.htm
3.
SchardtD., & SorkinB. (2002). In from the cold: Do supplements work?Nutrition Action Newsletter, 29(2), 1–6.