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://journals.vu.lt./LMR/article/view/34613. Acesso em: 19 apr. 2025.