I don't know if this the way I should be going about this, but I need either websites or books. Mainly in Linear Algebra, multilinear Algebra, category theory, and graph theory. I mean It would be cool to find these types of books at the graduate level. I mean, I want to be a mathematician and the only book I have currently is a book on linear algebra. Also, why are math books so expensive, I found this book on multilinear algebra and it cost 175 bucks and then I found a book on category theory which cost about 120, talk about over priced... But I guess the material in those book must be top shelf material.