@article{MZ_1926__25_167901,
     author = {W. Blaschke},
     title = {\"Uber die {Geometrie} von {Laguerre.} {VII.} {Kugelsysteme} {Ribaucours} und vierfache {Orthogonalsysteme}},
     journal = {Mathematische Zeitschrift},
     pages = {658--660},
     publisher = {mathdoc},
     volume = {25},
     year = {1926},
     zbl = {52.0766.01},
     url = {http://geodesic.mathdoc.fr/item/MZ_1926__25_167901/}
}