This "Die kleine Übung" by Hans-Martin Linde was amongst the first purchases that I made whilst still a young Petty Officer on H.M.S. Lofoten in November 1965. There are 24 exercises each of varying difficulty. At the time of purchase, my German was limited so that I was not able to take full advantage of this German language tutor. With hindsight, I've learned that it is not a particularly good idea for a beginner to carry out such exercises unsupervised. Years later, I had the greatest difficulty unlearning all the bad habits which I acquired in this period.
For all that, this is an excellent tutor which I can well recommend.