Centers for Disease Control and Prevention. What is HPV? https://www.cdc.gov/hpv/parents/whatishpv.html. Updated December 28, 2015. Accessed December 2016.
National Institutes of health. National Cancer Institute. Human Papillomavirus (HPV) Vaccines. https://www.cancer.gov/about-cancer/causes-prevention/risk/infectious-agents/hpv-vaccine-fact-sheet. Updated November 2, 2016. Accessed November 2016.
What is HPV? NHS Choices. http://www.nhs.uk/chq/Pages/2611.aspx. Updated December 15, 2015. Accessed December 2016.
The HPV connection. Oral Cancer Foundation. http://oralcancerfoundation.org/understanding/hpv/. Accessed September 2016.