For grammar study, I do recommend em Übungsgrammatik für die Mittelstufe. It combines excellent explanations with plenty of exercises. There are some pages dedicated to review of the beginner grammar such as the declensions, but just very quickly, and most of the book covers intermediate-level grammar in good detail. read more
I've been working with German in 10 Minutes a Day (good starter, easy to outpace), German Verb Drills, 500 German Verbs, and a dictionary. read more