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3. Centers for Disease Control and Prevention 2010 Streptococcus pneumoniae http://www.cdc.gov/abcs/reports-findings/survreports/spneu09.pdf
4. Age-related immune response to pneumococcal polysaccharide vaccination: lessons for the clinic;Iyer;Exp. Rev. Vac.,2015
5. 2014 The top 10 causes of death http://www.who.int/mediacentre/factsheets/fs310/en/index4.html