1. Centers for Disease Control and Prevention. Recommended childhood immunization schedule: United States, 1999. MMWR Morb Mortal Wkly Rep. 1999;48:12–16
2. American Association for Public Opinion Research. Standard Definitions. Ann Arbor, MI: American Association for Public Opinion Research; 1998. Available at: www.aapor.org/pdfs/standarddefs_3.1.pdf. Accessed December 5, 2005
3. Smith PJ, Simpson D, Battaglia, MP, et al. Split sampling design for topical modules in the National Immunization Survey. In: 2000 Proceedings of the Section on Survey Research Methods. Alexandria, VA: American Statistical Association; 2000:653–658. Available at: www.amstat.org/sections/srms/Proceedings/papers/2000_109.pdf. Accessed August 15, 2005
4. Smith PJ, Hoaglin DC, Battaglia MP, et al. Statistical methodology of the National Immunization Survey, 1994–2002. Vital Health Stat 2. 2005;(138):1–55. Available at: www.cdc.gov/nchs/data/series/sr_02/sr02_138.pdf. Accessed August 15, 2005
5. Research Triangle Institute. SUDAAN User's Manual, Release 8.0. Research Triangle Park, NC: Research Triangle Institute; 2002