Which Grammar book can I use on Level A1-B1?

I recommend a grammar book with exercises. You have 2 options. I use both of them in my lessons.

Grammatik Aktiv

Everything is in German –  explained in a very easy and helpful manner.

Link for Euros

Link for Pounds

A-Grammatik

Everything is in German and english – explained in a very easy and helpful manner.

Link for Euros

Link for Pounds