Edition Dux Kleine Notenrätsel Violin+Bass, Little Music Puzzle Book, By Guido Klaus: 26 riddles in violin and bass clef for beginners, Learn the natural notes in a playful way, Child-oriented design, For Piano,Accordion,Keyboard,And many more, 18 x 25 cm, 40 pages, Edition Dux D1044, ISBN978-3-86849-279-8, In German language