Sacks, Gerald E. <br/><br/>
Degrees of unsolvability   

 - 2nd. 
 - New Jersey  Princeton University Press  1966 
 - ix, 174p. Bibl. 
 - Annals of Mathematics studies    55 .
<br/><br/>  
<br/><br/><label>Dewey Class. No.: </label>511.3  / Sa121.DU