@article{ADM_2011_11_1_a6,
     author = {Bo\.zena Piekart and Andrzej Walendziak},
     title = {On filters and upper sets in {CI-algebras}},
     journal = {Algebra and discrete mathematics},
     pages = {109--115},
     publisher = {mathdoc},
     volume = {11},
     number = {1},
     year = {2011},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ADM_2011_11_1_a6/}
}