Can you refer me to books that are at the same advanced level of real analysis via measure theory as Folland's and Royden's books? I want to have a solid foundation and I've been referred to books like Cohn's and Axler's, but I don't have deep knowledge of real analysis (I'm still going to start studying introduction to analysis) and I don't know if these books combine measure theory and real analysis like the ones I mentioned in the title or whether they are purely measure theory. If possible it was a Dover book because they have affordable prices here in Brazil.
Thanks to everyone who can help me.