@article{CMUC_1972__13_2_a7,
     author = {Fu\v{c}{\'\i}k, Svatopluk and Ne\v{c}as, Jind\v{r}ich and Sou\v{c}ek, Ji\v{r}{\'\i} and Sou\v{c}ek, Vladim{\'\i}r},
     title = {Strengthening upper bound for the number of critical levels of nonlinear functionals},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {297--310},
     publisher = {mathdoc},
     volume = {13},
     number = {2},
     year = {1972},
     mrnumber = {0305169},
     zbl = {0253.58006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1972__13_2_a7/}
}