The volume of literature on the Kirchenkampf is expanding at an accelerating rate. Several bibliographical articles have already appeared, the most recent of which is by the Canadian scholar, John S. Conway. Of the 63 titles of books, articles, and collections discussed by Conway, 47 were published in the 1960s. Nearly all studies of the Kirchenkampf either defend or criticize the church in varying degrees. Most of the older accounts, as Conway points out in the introduction to his own comprehensive study, were written by clergymen and historians who actually participated in the Kirchenkampf. These scholars selected those facts which demonstrated that the church steadfastly, if not always effectually, opposed National Socialist tyranny in word and deed. The larger volume of Protestant works emphasized the activity of the Confessing Church, while the unaccountably smaller number of Roman Catholic accounts focused upon particular bishops and priests who protested courageously and suffered imprisonment or martyrdom. During the past ten years, however, a small group of mostly younger historians have published works sharply critical of the Roman Catholic Church in particular. These historians, the most prominent of whom are Gordon Zahn, Hans Müller, and Guenter Lewy, assert that the Roman Catholic Church failed to exert the kind of moral and political leadership which might have mitigated the horrors of National Socialism.