@article{CMH_1978__53_139739,
     author = {Werner B\"ani},
     title = {Quadratische {R\"aume} mit zwei {Unterr\"aumen.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {322--333},
     year = {1978},
     volume = {53},
     zbl = {0386.15022},
     url = {http://geodesic.mathdoc.fr/item/CMH_1978__53_139739/}
}