MORAN, D. A. Raising the Differentiability Class of a Manifold in Euclidean Space. The Journal of the Indian Mathematical Society, [S. l.], v. 29, n. 3, p. 119–133, 1965. DOI: 10.18311/jims/1965/16831. Disponível em: https://informaticsjournals.com/index.php/jims/article/view/16831. Acesso em: 5 may. 2024.