@article{10_21136_CMJ_1973_101205,
     author = {Zaj{\'\i}\v{c}ek, Lud\v{e}k},
     title = {On the intersection of the sets of the right and left internal approximate derivatives},
     journal = {Czechoslovak Mathematical Journal},
     pages = {629--634},
     publisher = {mathdoc},
     volume = {23},
     number = {4},
     year = {1973},
     doi = {10.21136/CMJ.1973.101205},
     mrnumber = {0323969},
     zbl = {0272.26004},
     language = {en},
     url = {https://geodesic-test.mathdoc.fr/articles/10.21136/CMJ.1973.101205/}
}