PLAZA, Ángel. Proof without words: Knopp series for (pi). Teaching Mathematics and Computer Science, [S. l.], v. 4, n. 2, p. 451–452, 2006. DOI: 10.5485/TMCS.2006.0143. Disponível em: https://ojs.lib.unideb.hu/tmcs/article/view/14784. Acesso em: 25 nov. 2024.