00290nam a2200109Ia 4500082002300000100003600023245004700059260004900106300001500155500000500170700000500175  a338.01(73)bK33.PT  aKendrick, J. W. and Pech, M. R.  aProductivity trends in the United Statesb  aNew JerseybPrinceton University Pressc1961  alii, 630p.  a  a