Not to be sold outside the 



United States of America 



or Canada 



Copyright 



1961 

 PERGAMON PRESS LTD 



AMERICAN EDITION 1961 



under license from 



Pergamon Press Ltd 



Library of Congress Card No. 61-10645 



Printed in Polaiul to tite order of Pai'isfwowe Wydawnictwo Naii/<owe 

 by Drul<arnia Uniwersytetii Jagiellonsl<ie^o. Cracow 



