https://www.reddit.com/r/mildlyinfuriating/comments/6l6nz8/this_crossword_that_requires_two_letter_per/
origin - http://www.pipiscrew.com/2017/07/this-crossword-that-requires-two-letter-per-square-in-some-spots/ this-crossword-that-requires-two-letter-per-square-in-some-spots