@article{CMH_1980__55_139821,
     author = {C. Riedtmann},
     title = {Algebren, {Darstellungsk\"ocher,} {Ueberlagerungen} und zur\"uck.},
     journal = {Commentarii mathematici Helvetici},
     pages = {199--224},
     publisher = {mathdoc},
     volume = {55},
     year = {1980},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/CMH_1980__55_139821/}
}