@article{MZ_1977__156_172574,
     author = {Walter Rautenberg},
     title = {Der {Verband} der normalen verzweigten {Modallogiken.}},
     journal = {Mathematische Zeitschrift},
     pages = {123--140},
     publisher = {mathdoc},
     volume = {156},
     year = {1977},
     zbl = {0414.03011},
     url = {http://geodesic.mathdoc.fr/item/MZ_1977__156_172574/}
}