@article{GDZPPN002087367,
title = {The Minimal Number of Critical Points of a Function on a Compact Manifold and the Lusternik-Schnirelman Category.},
journal = {Inventiones mathematicae},
volume = {5},
year = {1968},
pages = {197-244},
zbl = {0198.56603},
url = {http://dml.mathdoc.fr/item/GDZPPN002087367}
}
TAKENS, F. The Minimal Number of Critical Points of a Function on a Compact Manifold and the Lusternik-Schnirelman Category.. Inventiones mathematicae, Tome 5 (1968) pp. 197-244. http://gdmltest.u-ga.fr/item/GDZPPN002087367/