History Of Sudoku

http://m.psychologytoday.com/blog/brain-workout/200906/the-appeal-sudoku

Sudoku is good:

1. http://www.telegraph.co.uk/news/science/science-news/7415027/Doing-crosswords-or-sudoku-helps-couples-get-over-arguments.html
2. https://www.psychologytoday.com/blog/brain-workout/200906/the-appeal-sudoku