Journal Article
                        
                        O'Brien, Katherine L, Laura J Wolfson, James P Watt, Emilie  Henkle, Maria  Deloria-Knoll, Natalie  McCall, Ellen  Lee, Kim  Mulholland, Orin S Levine, and Thomas  Cherian.  
"Burden of disease caused by Streptococcus pneumoniae in children younger than 5 years: global estimates." The Lancet 374, no. 9693 (2009): 893-902.