Theory of linear operators in Hilbert space  
Akhiezer, N. I. 
 - New York :  Dover Publications,  1993 
 - xi, 218 p. ;  22 cm. 
<br/><br/> Originally published: New York : F. Ungar Pub. Co., c1961-c1963. | Two volumes bound as one." 
<br/><br/><label>ISBN: </label>0486677486 (pbk.) :