Lefschetz, S.. <br/><br/>
Contributions to the Theory of Nonlinear Oscillations /  

 - 1st ed /  
 - Princeton :   Princeton University Press ,   1987 
 - p.211 :  
<br/><br/><label>Subjects--Topical Terms: </label><br/>Nonlinear oscillations
<br/><br/><label>Dewey Class. No.: </label>B33  / J8