Levinson, Norman. <br/><br/>
Gap and density theorems :   

 - New York :  American Mathematical Society,  1940. 
 - viii, 246 pages. 
<br/><br/><label>ISBN: </label>082181026x 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Exponential functions.<br/>Fourier series.<br/>Functions of complex variables.<br/>Harmonic analysis.<br/>Integral equations.<br/>Mathematics.
<br/><br/><label>LC Class. No.: </label>QA404.L58