@article{1077378124, author = {Gray, Alfred}, title = {Principal curvature forms}, journal = {Duke Math. J.}, volume = {36}, number = {1}, year = {1969}, pages = { 33-42}, language = {en}, url = {http://dml.mathdoc.fr/item/1077378124} }
Gray, Alfred. Principal curvature forms. Duke Math. J., Tome 36 (1969) no. 1, pp. 33-42. http://gdmltest.u-ga.fr/item/1077378124/