@article{00702465, title = {Transnormal graph surfaces.}, journal = {Beitr\"age zur Algebra und Geometrie}, volume = {35}, year = {1994}, pages = {141-145}, zbl = {0804.53084}, language = {en}, url = {http://dml.mathdoc.fr/item/00702465} }
d'Azevedo Breda, A.M.; Craveiro de Carvalho, Francisco José. Transnormal graph surfaces.. Beiträge zur Algebra und Geometrie, Tome 35 (1994) pp. 141-145. http://gdmltest.u-ga.fr/item/00702465/