@article{MZ_1969__110_171171,
     author = {Erich Glock},
     title = {Polarit\"aten von endlich erzeugten freien {Ebenen.}},
     journal = {Mathematische Zeitschrift},
     pages = {257--296},
     publisher = {mathdoc},
     volume = {110},
     year = {1969},
     zbl = {0175.47702},
     url = {http://geodesic.mathdoc.fr/item/MZ_1969__110_171171/}
}