Kaumpera, A. and Spencer, D. C. <br/><br/>
Systems of linear partial differential equations and deformation of pseudogroup structures   

 - Montreal  Universite de Montreal  1974 
 - 104p. 
 - University of Montreal, seminaire de Mathematiques superieures-ETE 1969   v. 41 .
<br/><br/>  
<br/><br/><label>Dewey Class. No.: </label>515.35  / K96.SL