if you have the Russian paper, which I do not, Google translate should do a satisfactory job; I tried it on a related paper by Onishchik, for which I do have the source: Semi-simple decompositions of semi-simple Lie algebras. A pass of the first paragraph through Google translate produces a result that seems quite workable:
I don't read Russian: no edits on my part, other than formatting.
Let $G$ be a Lie algebra, let $G'$ and $G''$ be its subalgebras, we say that the triple ($G, G', G''$) is a decomposition if $G = G' + G''$. A Lie group acting on a manifold $M$ is called locally transitive if at least one of its orbitals on $M$ is open. It is easy to see that studying decompositions of real Lie algebras is equivalent to studying the inclusion relations between locally transitive groups.
Lee transformations. If $G$ is a complex Lie algebra, $G'$ and $G''$ are its complex subalgebras, then the decomposition $(G, G', G'')$ is said to be complex. The decomposition is said to be semisimple if $G, G'$, and $G''$ are semisimple.The present paper is devoted to finding all the real and complex semisimple expansions.