@article{GDZPPN000366854,
title = {New Bounds for Lower Envelopes in Three Dimensions, with Applications to Visibility in Terrains.},
journal = {Discrete \& computational geometry},
volume = {11},
year = {1994},
pages = {313-326},
zbl = {0819.68136},
url = {http://dml.mathdoc.fr/item/GDZPPN000366854}
}
Sharir, M.; Halperin, D. New Bounds for Lower Envelopes in Three Dimensions, with Applications to Visibility in Terrains.. Discrete & computational geometry, Tome 11 (1994) pp. 313-326. http://gdmltest.u-ga.fr/item/GDZPPN000366854/