@article{MAN_1970__187_162030,
     author = {K. D\"orge and H.A. JUNG},
     title = {Abschlie{\ss}ungen in {Klassen} strukturierter {Mengen.}},
     journal = {Mathematische Annalen},
     pages = {332--338},
     year = {1970},
     volume = {187},
     zbl = {0185.01701},
     url = {http://geodesic.mathdoc.fr/item/MAN_1970__187_162030/}
}