1. National Center for Health Statistics (2010) National Health and Nutrition Examination Survey (NHANES). Available: http://www.cdc.gov/NCHS/nhanes.htm. Accessed 2013 March 29.
2. National Center for Health Statistics (2010) Behavioral Risk Factor Surveillance System (BRFSS). Available: http://cdc.gov/brfss. Accessed 2013 March 29.
3. National Center for Health Statistics (2010) National Health Interview Survey. Available: http://www.cdc.gov/nchs/nhis.htm. Accessed 2013 March 29.
4. Pearce N, Beasley R, Burgess C, Crane J (1998) Asthma Epidemiology: Principles and Methods. Oxford University Press, USA. p. 266.
5. Asthma burden in a citywide, diverse sample of elementary schoolchildren in Chicago;MU Shalowitz;Ambul Pediatr,2007