@article{1029001146, author = {Beer, Gerald}, title = {Continuity properties of the visibility function.}, journal = {Michigan Math. J.}, volume = {20}, number = {4}, year = {1974}, pages = { 297-302}, language = {en}, url = {http://dml.mathdoc.fr/item/1029001146} }
Beer, Gerald. Continuity properties of the visibility function.. Michigan Math. J., Tome 20 (1974) no. 4, pp. 297-302. http://gdmltest.u-ga.fr/item/1029001146/