David Singmaster

David Breyer Singmaster (born 1939, USA) is a retired professor of mathematics at London South Bank University, England, UK. A self-described metagrobologist, he has a huge personal collection of mechanical puzzles and books of brain teasers. He is most famous for being an early adopter and enthusiastic promoter of the Rubik's Cube. <a href="https://en.wikipedia.org/wiki/David_Singmaster">wikipedia</a>