@article{2511,
author = {Nadler, Sam B. jr.},
title = {Coverings by closed sets},
journal = {Portugaliae mathematica},
volume = {26},
year = {1967},
pages = {51-61},
zbl = {0186.56103},
mrnumber = {0248747},
language = {en},
url = {http://dml.mathdoc.fr/item/2511}
}
Nadler, Sam B. jr. Coverings by closed sets. Portugaliae mathematica, Tome 26 (1967) pp. 51-61. http://gdmltest.u-ga.fr/item/2511/