00249nam a2200109Ia 4500082002800000100001700028245004000045260003400085300001000119500000500129700000500134  a338.476338952bAl428.NR  aAllen, P. W.  aNatural rubber and the syntheticsb  aLondonbGrosby Lockwoodc1972  a255p.  a  a