@article{GDZPPN002227843,
title = {Lusternik-Schnirelmann category and minimal coverings with contractible sets.},
journal = {Manuscripta mathematica},
volume = {58},
year = {1987},
pages = {37-46},
zbl = {0643.55002},
url = {http://dml.mathdoc.fr/item/GDZPPN002227843}
}
Clapp, Mónica; Montejano, Luis. Lusternik-Schnirelmann category and minimal coverings with contractible sets.. Manuscripta mathematica, Tome 58 (1987) pp. 37-46. http://gdmltest.u-ga.fr/item/GDZPPN002227843/