Challenging Sudoku Twelve Logic Puzzles (Vol 1)
Chapter 18: Two Challenging (DiffLev 19-20) Backpointers Puzzles (numbers 115-116)
- Step-by-step instructions for solving Puzzle 115, (98/144) Diff: 19/976.3435.9563.1A12.4897
- Step-by-step instructions for solving Puzzle 116, (94/144) Diff: 20/8424.5573.3B44.4523.6992