The Religious roles of the papacy: ideals and realities, 1150-1300 /
edited by Christopher Ryan 
. - Toronto : Pontifical Institute of Mediaeval Studies,  1989 
. - xii, 476 p.  ill.  24 cm. 
 - Papers in mediaeval studies  8 .
<br/><label>  ISBN: </label>0-88844-808-2