Logan <br/><br/>
Invariant Variational Principles 

 -  Academic Press  1977 
 - Mathematics in Science and Engineering .
<br/><br/><label>ISBN: </label>9780124547506 
<br/><br/><label>Subjects--Topical Terms: </label><br/> General<br/>Calculus of variations.,Invariants.,Transformations (Mathematics)<br/>MATHEMATICS