- 1500 Sudoku Brain Teaser X with solutions: Level 3 (medium), Volume 6
- 750 Sudoku Brain Teaser 16x16 mit Lösungen: Level 3 Volume 5
- 500 Sudoku Brain Teaser Variants Level 4 Vol. 2: with solutions
- 1500 Sudoku Brain Teaser 9x9 with solutions: Level 1-2 Volume 4
- 1500 Sudoku Brain Teaser 9x9 with solutions: Level 4-5 Volume 10






























