Hermann, Robert <br/><br/>
Geometry of non-linear differential equations,backlund transformations and solutions  Pt.A. 

 -  1976 
<br/><br/><label>Subjects--Uniform Titles: </label><br/>Transformations<br/>Non-linear differential equations
<br/><br/><label>Dewey Class. No.: </label>515.35  / H57G