@article{MASLO_1994__44_2_a5,
     author = {Porubsk\'y, \v{S}tefan},
     title = {Identities involving covering systems. {I.}},
     journal = {Mathematica slovaca},
     pages = {153--162},
     publisher = {mathdoc},
     volume = {44},
     number = {2},
     year = {1994},
     mrnumber = {1282532},
     zbl = {0809.11012},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/MASLO_1994__44_2_a5/}
}