BORYS, C. A groupoid picture of the Elek algebras. MATHEMATICA SCANDINAVICA, [S. l.], v. 127, n. 2, p. 185–208, 2021. DOI: 10.7146/math.scand.a-122419. Disponível em: https://www.mscand.dk/article/view/122419. Acesso em: 19 sep. 2021.