@article{CMUC_1976_17_1_a11,
     author = {Kastl, Jan},
     title = {Die $K$-abgeschlossenen {Teilmengen} der {Halbgruppen}},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {135--146},
     year = {1976},
     volume = {17},
     number = {1},
     mrnumber = {0404509},
     zbl = {0359.20067},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1976_17_1_a11/}
}