Webum > Games > Puzzles > Self-Referential Sentences Gallery of Mathematics / Self-referential Sentences Produced by Andy Burbanks. Good explanation with examples. Self-Referential Sentences Exhaustive lists of "This sentence has three a's" sentences. Solve my base three numerical self-referential sentences puzzle! The object of this difficult puzzle is to make four sentences mutually truthful by filling in base three numbers. Help build the biggest human edited directory on the internet Add your website - Open Directory Project - Become an editor