WEIER, J. Relationen zwischen Divergenz und Rotation. MATHEMATICA SCANDINAVICA, [S. l.], v. 11, p. 91–102, 1962. DOI: 10.7146/math.scand.a-10652. Disponível em: https://www.mscand.dk/article/view/10652. Acesso em: 5 may. 2024.