SZULKIN, A. Local structure of the zero-sets of differentiable mappings and application to bifurcation theory. MATHEMATICA SCANDINAVICA, [S. l.], v. 45, p. 232–242, 1979. DOI: 10.7146/math.scand.a-11838. Disponível em: https://www.mscand.dk/article/view/11838. Acesso em: 3 may. 2024.