lol that category is broad too. There are actual textbooks (mostly math/physics), stuff like the food lab, stuff like gardening, random carpentry/home repair/landscaping, and all kinds of other random stuff. Nowhere near all of it gets applied, but those are all separate (probably because I don't read them start to finish like I would fiction or other nonfiction) and I don't really track them at all. It's kind of arbitrary when you stop to think about it, though.