@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/