On the Transformations Preserving Asymptotic Directions of Hypersurfaces in the Euclidean Space. European Journal of Pure and Applied Mathematics, Maryland, USA, v. 2, n. 4, p. 564–573, 2009. Disponível em: https://ejpam.com/index.php/ejpam/article/view/459.. Acesso em: 3 may. 2024.