Difficult Sudoku Twelve Logic Puzzles (Vol 1)
Chapter 40: Two Difficult (DiffLev 11-12) Overstudying Puzzles (numbers 159-160)
- Step-by-step instructions for solving Puzzle 159, (91/144) Diff: 11/888.6779.9963
- Step-by-step instructions for solving Puzzle 160, (91/144) Diff: 12/9987.9753.6963