German Verb Drills, Fifth Edition (NTC FOREIGN LANGUAGE) Paperback – 7 Mar. 2017

I have to say this is the best German workbook I have. It's really clear, uses good examples, and builds on relevant vocabulary. It has plenty of exercises to practice and enough space to write in the book.It does just focus on verbs and tenses, which means it doesn't cover cases and other aspects of the language, so other books are needed. But in terms of layout and content, it is an essential buy for beginners/intermediate (I'm about level A2/B1).