@article{1214436221, author = {Hebda, James J.}, title = {The regular focal locus}, journal = {J. Differential Geom.}, volume = {16}, number = {3}, year = {1981}, pages = { 421-429}, language = {en}, url = {http://dml.mathdoc.fr/item/1214436221} }
Hebda, James J. The regular focal locus. J. Differential Geom., Tome 16 (1981) no. 3, pp. 421-429. http://gdmltest.u-ga.fr/item/1214436221/