@article{MZ_1936__41_168649,
     author = {L. Koschmieder},
     title = {Adjungierte {Extremalf} lachen im vierstufigen {R\"aume}},
     journal = {Mathematische Zeitschrift},
     pages = {43--55},
     publisher = {mathdoc},
     volume = {41},
     year = {1936},
     zbl = {0013.41702},
     url = {http://geodesic.mathdoc.fr/item/MZ_1936__41_168649/}
}