@article{BAG_1985__19_138302,
     author = {Gerhard Heidekr\"uger and Karel Zimmermann},
     title = {Eigenschaften offener und affiner {Mengen} in {Verbandsstrukturen}},
     journal = {Beitr\"age zur Algebra und Geometrie},
     pages = {177--192},
     publisher = {mathdoc},
     volume = {19},
     year = {1985},
     zbl = {0564.52001},
     url = {http://geodesic.mathdoc.fr/item/BAG_1985__19_138302/}
}