@article{CMH_1978__53_139752,
     author = {Borge Jessen},
     title = {Einige {Bemerkungen} zur {Algebra} der {Polyeder} in nicht-euklidischen {R\"aumen.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {525--528},
     publisher = {mathdoc},
     volume = {53},
     year = {1978},
     zbl = {0395.51013},
     url = {http://geodesic.mathdoc.fr/item/CMH_1978__53_139752/}
}