Emerg Infect DiseidEmerging Infectious Diseases1080-60401080-6059Centers for Disease Control89032122639828Research ArticleInvasive penicillin-resistant pneumococcal infections: a prevalence and historical cohort study.KronenbergerC. B.HoffmanR. E.LezotteD. C.MarineW. M.Department of Preventive Medicine and Biometrics, University of Colorado Health Sciences Center, Denver, Colorado, USA.Apr-Jun199622121124