@article{CMUC_1977_18_4_a11,
     author = {Simon, Petr},
     title = {Covering of a space by nowhere dense sets},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {755--761},
     year = {1977},
     volume = {18},
     number = {4},
     mrnumber = {0464133},
     zbl = {0373.54009},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1977_18_4_a11/}
}