Dic SonneveldDic Sonneveld was an Information and Computer Technology (ICT) professional at Leiden University. Jerry knew him as designer of a type of mechanical puzzles, using partly self-written software. In 1997 Jerry asked him to contribute to the research fo the history of the Chinese Puzzle, better known as Tangram (which was an international puzzle rage in the early 19th century). From that time on he assisted Jerry with literature research, library research and Internet research, which resulted in the 15 Puzzle Book (about the worldwide puzzle craze in 1880) and several others. All these experiences and knowledge now have culminated in the research for this book about Roman-Celtic mask puzzle padlocks. It all started in January 2013, as always, with Jerry's simple question; he wanted to know more about these "ancient trick locks". Read More Read Less