Bogoliubov, N. N. Mitropolsky, Y. A. <br/><br/>
Asymptotic methods in the theory non-linear oscillation 

 - Delhi  Hindustan  1961 
 - 534p. 
<br/><br/><label>Subjects--Uniform Titles: </label><br/>Oscillations
<br/><br/><label>Dewey Class. No.: </label>531.322  / B65A