@article{BAG_1971__1_138081,
     author = {B. KUMMER},
     title = {\"Uber {Schreiersche} {Erweiterungen} von universalen {Algebren} {I}},
     journal = {Beitr\"age zur Algebra und Geometrie},
     pages = {201--219},
     publisher = {mathdoc},
     volume = {1},
     year = {1971},
     zbl = {0242.08006},
     url = {http://geodesic.mathdoc.fr/item/BAG_1971__1_138081/}
}