@article{CMUC_1966__7_4_a9,
     author = {Ne\v{c}as, Jind\v{r}ich and Porack\'a, Zita},
     title = {On extrema of functionals},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {509--520},
     publisher = {mathdoc},
     volume = {07},
     number = {4},
     year = {1966},
     mrnumber = {0208440},
     zbl = {0157.22102},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1966__7_4_a9/}
}