Tritton, A. S. , <br/><br/>
The caliphs and their non-muslim subjects :  a critical study of the covenant of Umar /  Textual Documents 
by A. S. Tritton . 
 - London  Oxford Universsity Press 
 - 240p:  23cm. 
<br/><br/><label>Subjects--Index Terms: </label>Persian & Arabic Caliphs, Non-muslim subjects G-Persian Arabic 
<br/><br/><label>Dewey Class. No.: </label>297.92