Proof theory 
Pohlers, Wolfram. 
 - Berlin :  Springer,  2009 
 - xiii, 370 p.; 24 cm. 
<br/><br/><label>ISBN: </label>9783540693185 (pbk.) | 3540693181 (pbk.) | 9783540693192 (e-ISBN) | 354069319X (e-ISBN)