@article{MZ_1975__145_172274,
     author = {Wilhelm Singhof},
     title = {On the {Lusternik-Schnirelmann} {Category} of {Lie} {Groups.}},
     journal = {Mathematische Zeitschrift},
     pages = {111--116},
     publisher = {mathdoc},
     volume = {145},
     year = {1975},
     zbl = {0315.55012},
     url = {http://geodesic.mathdoc.fr/item/MZ_1975__145_172274/}
}