1. https://www.census.gov/people/disability/publications/sipp2010.html
2. Evidence-based approaches to oral health promotion;Crall,2002
3. www.surgeongeneral.gov/topics/mentalretardation/retardation.pdf
4. http://iom.nationalacademies.org/Reports/2011/Improving-Access-to-Oral-Health-Care-for-Vulnerable-and-Underserved-Populations.aspx#sthash.1Y0pTNbw.dpuf