KAŠUBA, Romualdas. What is simple but exciting mathematical problem?. Lietuvos matematikos rinkinys, [S. l.], v. 41, n. spec., p. 369–376, 2001. DOI: 10.15388/LMR.2001.34613. Disponível em: https://www.journals.vu.lt/LMR/article/view/34613.. Acesso em: 10 may. 2024.