@article{10_21136_CMJ_1977_101483,
     author = {Porubsk\'y, \v{S}tefan},
     title = {Commutative semi-primary $x$-semigroups},
     journal = {Czechoslovak Mathematical Journal},
     pages = {467--472},
     publisher = {mathdoc},
     volume = {27},
     number = {3},
     year = {1977},
     doi = {10.21136/CMJ.1977.101483},
     mrnumber = {0457602},
     zbl = {0381.20047},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.1977.101483/}
}