1. Keja K, et al. Expanded programme on immunization. World Health Stat Q. 1988;41(2):59–63.
2. Mills EJ, Montori VM, Ross CP, Shea B, Wilson K, Guyatt GH. Systematically revieweing qualitative studies complement survey design: an exploratory study of barriers to paediatric immunisations. J Clin Epidemiologi. 2005;58:1101–8.
3. Fredrickson DD, Davis TC, Arnold LA, Kenne EM, Humiston SG, Cross JT, Bocchini JA. Childhood immunization refusal. Provider and parent perceptions. Clin Res Methods. 2004;36(6):431–9.
4. Freed GL, Clark SJ, Butchart AT, Singer DC, Davis MM. Parental vaccine safety concerns in 2009. J Am Acad Pediatrics. 2010;125:654–60.
5. Offit PA, Quarles J, Gerber MA, Hacket CJ, Marcuse EK, Kollman TR, Gellin BG, Landry S. Addressing parents concerns: do multiple vaccines overwhelm or weaken the Infant’s immune system? J Am Acad Pediatrics. 2002;109:124–9.