My beloved adrian_turtle just called, because she thought I could use a friendly voice and some reassurance. She was right. Among other things, she pointed out that even if I find the notebooks in question, they may not contain the information I'm looking for.

She also reminded me that if I decide to go look for them, I don't have to do it right now: it's reasonable to find the idea scary, and there's nothing that's about to happen, or needs to be done, that means it can't wait.