Zwiebach, Barton. <br/><br/>
A First course in string theory / 
Barton Zwiebach. 
 - 2nd  ed. 
 - Cambridge :  C. U. P.,  2009. 
 - xxii, 673  p. 
<br/><br/><label>ISBN: </label>0521880329 : 
<br/><br/><label>Subjects--Topical Terms: </label><br/>String models.