Kubarski, Jan. «A Criterion for the Minimal Closedness of the Lie Subalgebra Corresponding to a Connected Nonclosed Lie Subgroup». Revista Matemática Complutense 4, no. 2 (enero 1, 1991): 159. https://doi.org/10.5209/rev_REMA.1991.v4.n2.17950.