Logic Puzzles & Brain Games for Adults: 500 Easy to Hard Puzzles & 12 Puzzle Types (Sudoku, Fillomino, Battleships, Calcudoku, Binary Puzzle, ... Numbrix): 4 (Challenging Fun Brain Teasers)

Hard Logic Puzzles & Brain Games for Adults: 500 Puzzles & 12 Puzzle Types (Sudoku, Fillomino, Battleships, Calcudoku, Binary Puzzle, Slitherlink, ... 3 (Challenging Fun Brain Teasers Series)

Adult Activity Book: 500 Easy Logic Puzzles (Sudoku, Tridoku, Masyu, Hakyuu, Battleships, Fillomino, Suguru, Creek, Numbrix, Binary, Minesweeper and Futoshiki): 24 (Logic & Brain Teasers Series)

Adult Activity Book: 500 Hard Logic Puzzles (Sudoku, Tridoku, Masyu, Hakyuu, Battleships, Fillomino, Suguru, Creek, Numbrix, Binary, Minesweeper and Futoshiki): 26 (Logic & Brain Teasers Series)

Activity Book for Adults & Seniors: 500 Easy Logic Puzzles (Sudoku - Fillomino - Kakuro - Futoshiki - Hitori - Slitherlink - Killer Sudoku - Calcudoku ... Numbrix): 21 (Brain Games for Adults Series)