Excellent, thanks! I should probably mention, by the way, that in the 1930s and 40s, the word gay encompassed people who are understood as transgender today. So in today's parlance, it was both gay and trans people being killed and sent to the camps.

I've read the book you're recommending and I highly endorse it.

I also recommend Richard Plant's excellent "The Pink Triangle," the first comprehensive book in English on the subject.

Plant's book is arguably responsible for Act Up and Queer Nation modifying and adopting the pink triangle as logos. His collection of first person accounts brought the subject to public attention in the late 80s just as Act Up was searching for powerful symbology.