@article{JOLT_1991_1_1_a5,
     author = {U. Zimmermann},
     title = { Invariante {Kegel} in {Cartan-Algebren}},
     journal = {Journal of Lie Theory},
     pages = {55--64},
     year = {1991},
     volume = {1},
     number = {1},
     doi = {10.5802/jolt.6},
     zbl = {0746.22014},
     url = {https://jolt.centre-mersenne.org/articles/10.5802/jolt.6/}
}