Unsurprisingly that is the bibliography of one book: The Holy Reich: Nazi Conceptions of Christianity, 1919–1945 Several of those books don't even mention abortion.
This one though Catholic Citizens in the Third Reich: Psycho-social Principles and Moral Reasoning actually has a fairly long section dedicated to the objections, and public protest by the Church to Hitler's euthanasia programs (pp 224-250).
unsurprisingly...I DIDN'T LIST ALL OF THE BOOKS THAT.I.READ as part of the course or courses that I took...I didn't make you wet with synopsis for a dissertation on the subject...you asked for sources...you never said exhaustive or empirical sO I should have just listed M.A.D. & Viz...I suppose they would have satisfied...NOT...b4 u accuse me of ignorance check out you own. Just because mamma didn't give u booby wen u wuz a baby she wanted to throe out the window...quite frankly gives me turgid mirth...nowottameen?
The Catholic Historical Review: Volume 62 (1976) (p. 56) The "Right to Kill" in the Third Reich. Prelude to Genocide by Graham, Robert A., SJ actually has a pretty thorough history of the topic.
Also apparently youve never heard of Mit brennender Sorge (With burning concern), which was a papal encyclical issued in 1937 condeming Nazism in general. Also one of the first public attacks on the Nazis...