VOROZHTSOV, E. V. On Some Unsolved Problems of Mathematica. Engineering, Technology & Applied Science Research, Greece, v. 2, n. 4, p. 259–264, 2012. DOI: 10.48084/etasr.205. Disponível em: https://etasr.com/index.php/ETASR/article/view/205. Acesso em: 18 apr. 2024.