Is acceptable requesting books and materials for mathematical classes? Any body may need some textbooks or any materials for mathematics education. Can we accept this questions as high quality expert level questions ?
In general, I am against asking for book recommendations on this site simply because it is extremely easy to search for books on any subject and get reviews of those books. Instead of posting a question, searching on Amazon or a university's book store should yield more than enough information for the average person.
On the other hand, if someone is trying to find additional materials that are not covered in a textbook and cursory searches have yielded nothing of value, asking a question to find what other educators have used might be acceptable. Though I don't anticipate this type of thing coming up very often.