Donner, K <br/><br/>
Extension of positive operators & Korovkin theorems 
K. Donner 
 - Berlin  Springer  1982 
 - xii  182 
 - Lecture notes in mathematics 904 .
<br/><br/><label>ISBN: </label>3540111832 
<br/><br/><label>Dewey Class. No.: </label>5.03+22  / DONN