@article{1077375643, author = {O'Neill, Barrett}, title = {Umbilics of constant curvature immersions}, journal = {Duke Math. J.}, volume = {32}, number = {1}, year = {1965}, pages = { 149-159}, language = {en}, url = {http://dml.mathdoc.fr/item/1077375643} }
O’Neill, Barrett. Umbilics of constant curvature immersions. Duke Math. J., Tome 32 (1965) no. 1, pp. 149-159. http://gdmltest.u-ga.fr/item/1077375643/