Elsgolts, L. E. (Lev Ernestovich) <br/><br/>
Differential equations and calculus variations / 
tr. from the Russian by George Yankovsky. 
 - Moscow :  Mir Publishers,  1970. 
<br/><br/> Translation of Differentsialnye uravnenifa i variatsionnoe ischislenie. 
<br/><br/>Bibliography: p. [436]. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Differential equations.<br/>Calculus of variations.