@article{CMUC_1989__30_2_a1,
     author = {Koslowski, J\"urgen},
     title = {Topological hulls revisited},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {213--225},
     publisher = {mathdoc},
     volume = {30},
     number = {2},
     year = {1989},
     mrnumber = {1014121},
     zbl = {0677.18005},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1989__30_2_a1/}
}