L.V.Ovsiannikov & W.F.Ames <br/><br/>
Group Analysis of Differential Equations 

 - New York  Academic Press  1982 
 - xiv,416p.i 
<br/><br/><label>ISBN: </label>0-12-53-1801-1 
<br/><br/><label>Dewey Class. No.: </label>515.35