@article{CMUC_1994__35_4_a10,
     author = {N\'ajares, J. and Zaj{\'\i}\v{c}ek, L.},
     title = {A $\sigma$-porous set need not be $\sigma$-bilaterally porous},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {697--703},
     publisher = {mathdoc},
     volume = {35},
     number = {4},
     year = {1994},
     mrnumber = {1321240},
     zbl = {0822.26001},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1994__35_4_a10/}
}