@article{MZ_1969__112_171240,
     author = {Oddvar Iden},
     title = {Free {Planes.} {III.}},
     journal = {Mathematische Zeitschrift},
     pages = {289--295},
     publisher = {mathdoc},
     volume = {112},
     year = {1969},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/MZ_1969__112_171240/}
}