Some hours ago I asked a question regarding the holocaust, and thanks to this sub I got a great answer.

My previous question is here:
https://www.reddit.com/r/AskHistorians/comments/mj5cis/seeking_info_on_a_particular_holocaust_denial/

Now I know that talking with holocaust deniers can generally be a fruitless excercise. But in anticipation of crossing paths with a denier in my social circle, I decided to re-inforce my general knowledge of the holocaust. So I hit up yadvashem.org and https://encyclopedia.ushmm.org.

These are great for providing general and detailed overviews.

Then I got interested particularly in Operation Reinhard - the extermination of Jews living in Poland.

I'd like to know: what are the primary sources for studying Operation Reinhard?

And also of these primary sources, which of those sources have copies that might be available online?

Thanks.