1. The next four decades the older population in the United States: 2010 to 2050;Vincent,2010
2. Demographic trends in the 20th century: census 2000 special reports;Hobbs,2002
3. 2006 National Hospital Discharge Survey;DeFrances;Natl Health Stat Report,2008
4. National Hospital Discharge Survey: 2007 summary;Hall;Natl Health Stat Report,2010
5. Ambulatory surgery in the United States, 2006;Cullen;Natl Health Stat Report,2009