Lefschetz, S,  <br/><br/>
Contributions to the theory of nonlinear oscillations, Vol.4 
S Lefschetz  
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 - Princeton University Press, New Jersey  1958 
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 - Annals of Mathematics Studies, Vol.041 .
<br/><br/><label>Subjects--Topical Terms: </label><br/>Annals of Mathematics Studies
<br/><br/><label>Dewey Class. No.: </label>R  AMS.041