Friedrich Prym - Wikipedia
Mathematician - Chessprogramming wiki
Wilhelminenstraße - Aschaffenburg
Mathematician - Chessprogramming wiki
Great Moravia: Most Up-to-Date Encyclopedia, News & Reviews
Friedrich Prym (1841-1915) :: museum-digital:rheinland
Pat'sBlog: On This Day in Math - April 1
Prym (Familie) - Wikiwand
Mathematician - Chessprogramming wiki
Wilhelm Conrad Röntgen - University Archives