KUSTAANHEIMO, Paul. On the relation of congruence in finite geometries. MATHEMATICA SCANDINAVICA, [S. l.], v. 5, p. 197–201, 1957. DOI: 10.7146/math.scand.a-10494. Disponível em: https://tidsskrift.dk/math/article/view/10494. Acesso em: 13 aug. 2026.