Complex homogeneous spaces of the Lie group $SO(2k+1,2l+1)$

Let $G$ be a connected Lie group, with Lie algebra which is the real form of the second category of type $D_n$. This paper lists all the connected closed subgroups $U$ of $G$ such that there exists a complex structure on the manifold $M=G/U$ which is invariant under $G$, and it also describes all such structures on $M$.
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