@article{MZ_1965__89_170446,
     author = {Hans-J\"urgen Hoehnke},
     title = {\"Uber das untere und obere {Radikal} einer {Halbgruppe.}},
     journal = {Mathematische Zeitschrift},
     pages = {300--311},
     year = {1965},
     volume = {89},
     zbl = {0201.36102},
     url = {http://geodesic.mathdoc.fr/item/MZ_1965__89_170446/}
}