Dhooge IJ, van Kempen MJ, Sanders LA, Rijkers GT (June 2002). "Deficient IgA and IgG2 anti-pneumococcal antibody levels and response to vaccination in otitis prone children". International Journal of Pediatric Otorhinolaryngology. 64 (2): 133–141. doi:10.1016/S0165-5876(02)00068-X. PMID12049826.
Dhooge IJ, van Kempen MJ, Sanders LA, Rijkers GT (June 2002). "Deficient IgA and IgG2 anti-pneumococcal antibody levels and response to vaccination in otitis prone children". International Journal of Pediatric Otorhinolaryngology. 64 (2): 133–141. doi:10.1016/S0165-5876(02)00068-X. PMID12049826.