1. U.S. Census Bureau Population projections of the United States by age, sex, race, and Hispanic origin: 1995 to 2050 www.census.gov/prod/1/pop/p25-1130.pdf 2010
2. U.S. Census Bureau The 2008 statistical abstract: estimates and projections. Table 10: resident population projections by sex and age, 2010 to 2050 www.census.gov/compendia/statab/2008/tables/08s0010.pdf 2010
3. U.S. Census Bureau Chapter 2: numerical growth www.census.gov/prod/1/pop/p23-190/p23190-f.pdf 2010
4. Mashabi S. The impact of externship programs on the clinical performance of senior dental students 2009
5. Evaluating externship programs: impact of program length on clinical productivity;Mascarenhas;J Dent Educ,2007