https://praguepig.com/2019/09/zdenek-princ-inventor-of-popular-childrens-memory-game-pexeso-dies-aged-85-princ-first-had-idea-while-working-on-mosaics-in-pragues-st-vitus-cathedral-in-the-1960s-idnes-cz-social-medi/
Zdenek Princ, inventor of popular children's memory game "Pexeso", dies, aged 85; Princ first had idea while working on mosaics in Prague's St. Vitus cathedral in the 1960s (iDNES.cz) [Social Media Post]