Reading Recommendations? Barth's & Bonhoeffer's False Gods

Hi internet - especially all you Barthians and Bonhoefferians (-ites?) out there.

I’m in the process of compiling a reading list, and I could use your suggestions.

Here’s my goal: to explore the possible relationship between Barth’s critique of the “No-God”(Nich-Gott) and Bonhoeffer’s critique(s) of viewing God as a “stopgap” (Lückenbüßer) or “working hypothesis.”

As far as primary sources go, I plan to focus on the Romans commentary, Garrett Green’s recent re-translation of CD §17, and Letters and Papers from Prison.

As for secondary sources, right now I’m starting the list with Tom Greggs’ Theology Against Religion. I’ve read this twice now, and it has been a major inspiration for the project.

I’ve also got my eye on Michael DeJonge’s Bonhoeffer’s Theological Formation, Ernst Feil’s The Theology of Dietrich Bonhoeffer, Andreas Pangritz’s Karl Barth in the Theology of Dietrich Bonhoeffer, and Jeffrey Pugh’s Religionless Christianity.

I’m also working my way through Sven Ensminger’s Karl Barth’s Theology as a Resource for a Christian Theology of Religions. While this looks very helpful for a larger project on Barth, Bonhoeffer, and the theological critique of religion, I’m still looking for sources that deal more directly with Barth’s “No-God” and Bonhoeffer’s God as “stopgap” or “working hypothesis.“ 

Do you have any reading recommendations for me? 

OR, even better: Have any of you translated Hans-Joachim Kraus’ Theologische Religionskritik into English yet? Because that would be fantastic.