@article{10_4064_aa_31_3_247_257,
     author = {Ladislav Skula},
     title = {On c-semigroups},
     journal = {Acta Arithmetica},
     pages = {247--257},
     publisher = {mathdoc},
     volume = {31},
     number = {3},
     year = {1976},
     doi = {10.4064/aa-31-3-247-257},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/aa-31-3-247-257/}
}