Contributions to the theory of nonlinear oscllations 

 - Princeton:   Princeton University Press,   1950. 
 - ix, 350 p.:   graf.;  
 - Annals of mathematics studies  no. 20 .
 - Annals of mathematics studies, No. 20 .
<br/><br/><label>Subjects--Topical Terms: </label><br/>OSCILLATION MODES<br/>ECUACIONES DIFERENCIALES<br/>ECUACIONES DIFERENCIALES ORDINARIAS