Subnormal structure of non-stable unitary groups over rings

Furthermore, we give a classification for the subnormal subgroups of the unitary group U(2n,R,Λ), which is an analog for the results existing in the general linear groups; see [L.N. Vaserstein, The subnormal structure of general linear groups over rings, Math. Proc. Cambridge Philos. Soc., 108 (1990) 219-229; N.A. Vavilov, Subnormal structure of general linear group, Math. Proc. Cambridge Philos. Soc. 107 (1990) 103-106; J.S. Wilson, The normal and subnormal structure of general linear groups, Proc. Cambridge Philos. Soc. 71 (1972) 163-177].