Logan, John David. <br/><br/>
Invariant variational principles / 
John David Logan. 
 - New York :  Academic Press,  1977. 
 - xv, 172 p. ;  24 cm. 
 - Mathematics in science and engineering ;  v. 138 .
 - Mathematics in science and engineering ;  v. 138. .
<br/><br/>Bibliography : p. 165-168. 
<br/><br/><label>ISBN: </label>0124547508 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Calculus of variations.<br/>Invariants.<br/>Transformations (Mathematics).