23 books • 4 series
Book #2: 5 Step Sudoku I For Addicts Vol 2
Book #4: 5 Step Sudoku I For Addicts Vol 4
Book #5: 5 Step Sudoku I For Addicts Vol 5
Book #1: 5 Step Sudoku I For Experts Vol 1
Book #2: 5 Step Sudoku I For Experts Vol 2
Book #3: 5 Step Sudoku I For Experts Vol 3
Book #2: 5 Step Sudoku II For Experts Vol 2
Book #4: 5 Step Sudoku II For Experts Vol 4
Book #5: 5 Step Sudoku II For Experts Vol 5
Book #1: 5 Step Sudoku I For Lovers Vol 1
Book #3: 5 Step Sudoku I For Lovers Vol 3