Edit: I phrased the question ambiguously it seems. I appreciate all answers, but basically I'm looking for a thorough and yet relatively quick way to review German grammar. With "book" I meant grammar book, although I'm open to other media. I am sorry if I was unclear....
Some time ago I had a pretty high level of German - high C1 or low C2? -- through study and living two years in German speaking countries. Time, lack of practice, and other foreign languages have somewhat eroded that. I'm keen to recuperate my skills. So I'm looking for books and other resources to help with a "re-infusion" of German, especially grammar and vocabulary. I have a lot of grammar "burned in" -- I know what's right without remembering why, just instinctually. Which is good. But there are many holes. I found a good series of books and swallowing my pride am starting with A1, although I have some concern that if I think too much about what I'm doing I might lose the instinct. I'll move from there to B and C levels. But I'd also like to get a parallel track going which will move me ahead quicker, as many parts of my abilities are still high level, and I don't want to sabotage myself by getting bored.
Books in German are fine -- I live in the EU so might be easier to get -- as well as English. Any other suggestions welcome. Danke vielmals!
