WITTMANN, Erich Christian. Operative Beweise in der Schul- und Elementarmathematik. mathematica didactica , [S. l.], v. 37, n. 2, p. 213–232, 2014. DOI: 10.18716/ojs/md/2014.1127. Disponível em: https://journals.ub.uni-koeln.de/index.php/mathematica_didactica/article/view/1127. Acesso em: 3 mai. 2024.