Fries, Heinrich, Rahner, Karl..
Unity of the Churches : an actual possibility /
translated by R.C.L. Gritsch, E.W. Gritsch 
. - Philadelphia ; New York/Ramsey  : Fortress Press ; Paulist Press,  1983 
. - XII, 146 p.  22 cm. 
<br/><label>  ISBN: </label>0-8006-1820-3