Fries, Heinrich, Rahner, Karl..
Unity of the Churches: An Actual Possibility /
Translated by Ruth C. L. Gritsch and Eric W. Gritsch 
. - Philadelphia; New York; Ramsey : Fortress Press; Paulist Press,  1984 
. - xii, 146 p.  22 cm. 
<br/><label>  ISBN: </label>0-8091-2671-0