@article{GDZPPN002306794,
title = {Lusternik-Schnirelman Theory and Non-Linear Eigenvalue Problems.},
journal = {Mathematische Annalen},
volume = {196},
year = {1972},
pages = {55-72},
zbl = {0233.47049},
url = {http://dml.mathdoc.fr/item/GDZPPN002306794}
}
Amann, Herbert. Lusternik-Schnirelman Theory and Non-Linear Eigenvalue Problems.. Mathematische Annalen, Tome 196 (1972) pp. 55-72. http://gdmltest.u-ga.fr/item/GDZPPN002306794/