@article{MASLO_1972__22_2_a1,
     author = {Mi\v{s}{\'\i}k, Ladislav},
     title = {Notes on an approximate derivative},
     journal = {Mathematica slovaca},
     pages = {108--114},
     publisher = {mathdoc},
     volume = {22},
     number = {2},
     year = {1972},
     mrnumber = {0315057},
     zbl = {0236.26002},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/MASLO_1972__22_2_a1/}
}