Kauffman, Robert M. and Others <br/><br/>
Deficiency index problem for powers of ordinary differential expressions   
By Robert M. Kauffman, Thomas T. Reed and Anton Zettl 
 - Berlin  Springer-Verlag  1977 
 - vi, 112p. 
 - Lecture notes in Mathematics   621 .
<br/><br/>  
<br/><br/><label>Dewey Class. No.: </label>515.35  / K21.DI