Kevin Birch
150 Medium Trios Sudoku Variation and Variants with Answers- 150 Medium Twins Sudoku Variation and Variants with Answers
- 180 Medium Sudoku Variation and Variants with Answers
- 200 EASY but Challenging 'Alphadoku' Puzzles - Sudoku with a Difference!
- 200 EASY but Challenging 'Dominoku' Puzzles - Sudoku Puzzles with a Twist!
- 200 EASY but Challenging 'Romadoku' Puzzles - Sudoku with a Difference!
- 200 Easy Sudoku Puzzles with Solutions for Kids of All Ages to Adult!
- 200 HARD and Challenging Sudoku Puzzles with Answers
- 200 HARD Sudoku Puzzles with Answers for Those Long Summer Days
- 200 MEDIUM and Challenging Sudoku Puzzles with Complete Answers
- 200 Medium Sudoku Puzzles with Answers for Those Long Summer Days
- 200 Sudoku Extreme Puzzles with Solutions