@article{ARM_1973_9_2_a4,
     author = {Zapletal, Josef},
     title = {Distinguishing subsets in semilattices},
     journal = {Archivum mathematicum},
     pages = {73--82},
     year = {1973},
     volume = {9},
     number = {2},
     mrnumber = {0364513},
     zbl = {0282.06005},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ARM_1973_9_2_a4/}
}