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G. M. Ekwurzel, J. S. Simmons, Louis I. Dublin, Lloyd D. Felton, Studies on Immunizing Substances in Pneumococci: VIII. Report on Field Tests to Determine the Prophylactic Value of a Pneumococcus Antigen, Public Health Reports (1896-1970), Vol. 53, No. 42 (Oct. 21, 1938), pp. 1877-1893
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Ekwurzel et al. (1938) studied this question.
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