@article{MASLO_2003__53_4_a2,
     author = {Porubsk\'y, \v{S}tefan and Sch\"onheim, Jochanan},
     title = {Old and new necessary and sufficient conditions on $(a_i, m_i)$ in order that $n\equiv a_i (\operatorname {mod} m_i)$ be a covering system},
     journal = {Mathematica slovaca},
     pages = {341--349},
     publisher = {mathdoc},
     volume = {53},
     number = {4},
     year = {2003},
     mrnumber = {2025467},
     zbl = {1071.11012},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/MASLO_2003__53_4_a2/}
}