Birkhoff, Garrett. <br/><br/>
Ordinary Differential Equations /  

 - Third Ed. /  
 - New York :   John Wiley and Sons ,   1987 
 - p.342,vii :  
<br/><br/><label>Subjects--Topical Terms: </label><br/>Mathematics 
<br/><br/><label>Dewey Class. No.: </label>B331  / L8