1. http://www.aarp.org/health/conditions-treatments/info-03-2011/8-germiest-places.html
2. https://www.researchgate.net/publication/224917391_Persistence_and_Transferability_of_Noroviruses_on_and_between_Common_Surfaces_and_Foods
3. Dr. Charles Gerba, University of Arizona, “Viruses spread ‘like crazy’ in an office.” Today.com, Sept. 8, 2014.
4. WHO Guidelines on Hand Hygiene in Health Care: First Global Patient Safety Challenge Clean Care Is Safer Care. Geneva: World Health Organization; 2009. 7, Transmission of pathogens by hands.
5. https://www.sciencedaily.com/releases/2014/09/140908093640.htm