Dover offers a lot of those classics:
https://store.doverpublications.com/by-subject-mathematics.h...
https://store.doverpublications.com/by-subject-mathematics.h...
That discouraged me a lot, being stuck on something that would have been handheld in an older work. From then on, I thought it would be better to seek out the aged books, so concepts would (possibly) be simplified, if only by the lack of a larger sphere of implicit prerequisites.
It's not always true, of course. Maybe it was just that one time or the teaching style. Math does not age, but explanations can always be modernized.
I would like to regularly peruse Math Overflow for exactly that.