Double Black Diamond Hard Sudoku

Double Black Diamond Hard Sudoku

Frank Longo2013
Warning: danger ahead! These treacherously tough puzzles all require upper-level solving techniques to conquer. So, if you want hard sudoku that's easy to take on the go, this Sit & Solve® collection is the ticket. Attractively packaged, it's a terrific gift or stocking stuffer for hardcore sudoku fans.
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