Hard Brain Teasers: Gappy Puzzles - Large Print for Fun Travel: Hard Puzzle Books, cartea 1

Gappy is played on a square grid. The aim is to blacken some cells of a grid according to the following rules:
- Each row and each column contains two black cells.
- No black cells touch each other, not even diagonally.
- Numbers outside the grid show the quantity of white cells between black cells in corresponding row or column.