@article{MZ_1978__159_172641,
     author = {Reinhard John},
     title = {G\"ultigkeitsbegriffe f\"ur {Gleichungen} in partiellen {Algebren.}},
     journal = {Mathematische Zeitschrift},
     pages = {25--36},
     publisher = {mathdoc},
     volume = {159},
     year = {1978},
     zbl = {0355.02009},
     url = {http://geodesic.mathdoc.fr/item/MZ_1978__159_172641/}
}