@article{TSG_1991-1992__10__9_0, author = {Jorge Sotomayor}, title = {Lines of curvature and umbilic points on surfaces}, journal = {S\'eminaire de th\'eorie spectrale et g\'eom\'etrie}, pages = {9--12}, publisher = {Institut Fourier}, address = {Grenoble}, volume = {10}, year = {1991-1992}, mrnumber = {1715907}, language = {en}, url = {https://tsg.centre-mersenne.org/item/TSG_1991-1992__10__9_0/} }