00340nam a22000737a 4500245017200000260006500172300001000237650001900247  aA study of infant mortality from linked records :bcomparison of neonatal mortality from two cohort studies, United States /cUS Dept. of Health, Education and Welfare  aMaryland :bUS Dept. of Health, Education and Welfarec1972.  a99 p.  aCohort studies