Geodesic
Subroups normalized by the commutator subgroup of the Levi subgroup
Zapiski Nauchnykh Seminarov POMI, Problems in the theory of representations of algebras and groups. Part 11, Tome 319 (2004), pp. 199-215 
V. G. Kazakevich; A. K. Stavrova. Subroups normalized by the commutator subgroup of the Levi subgroup. Zapiski Nauchnykh Seminarov POMI, Problems in the theory of representations of algebras and groups. Part 11, Tome 319 (2004), pp. 199-215. http://geodesic.mathdoc.fr/item/ZNSL_2004_319_a5/
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     title = {Subroups normalized by the commutator subgroup of the {Levi} subgroup},
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Voir la notice du chapitre de livre provenant de la source Math-Net.Ru

We describe subgroups of the unipotent radical of a maximal parabolic subgroup of a Chevalley group over a field normalized by the commutator subgroup of the Levi subgroup over a field $K$. It is shown that in the typical case such subgroups are in one-to-one correspondence with the closed subsets of $\{1,2,\dots,n\}$ for a natural $n$. In the exceptional cases the classification also involves additive subgroups of $K$. See the table in the paper for a detailed list of the possibilities.

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