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| Games / Puzzles / Brain_Teasers / Sudoku / Variants | |
| Mathematical Recreations | |
| Custom Word Doku puzzles devised by Steve Schaefer. Features an entire sentence embedded into the puzzle. | |
| http://www.mathrec.org/sudoku/ | |
| Science / Math / Recreations / Games_and_Puzzles | |
| Mathematical Recreations | |
| Detailed exploration of a selection of mathematical topics. | |
| http://www.mathrec.org/ | |