![The Protective Efficacy of Polyvalent Pneumococcal Polysaccharide Vaccine]()
The Protective Efficacy of Polyvalent Pneumococcal Polysaccharide VaccineShapiro, Eugene D.; Berg, Anne T.; Austrian, Robert; Schroeder, Donna; Parcells, Valerie; Margolis, Amy; Adair, Russell K.; Clemens, John D. · New England Journal of Medicine · 1991