@article{CMUC_1986_27_1_a6,
     author = {Matou\v{s}ek, Ji\v{r}{\'\i}},
     title = {Approximate symmetric derivative and monotonicity},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {83--86},
     year = {1986},
     volume = {27},
     number = {1},
     mrnumber = {843422},
     zbl = {0586.26004},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1986_27_1_a6/}
}