Glöckner, Helge, and George A. Willis. “Decompositions of Locally Compact Contraction Groups, Series and Extensions.”https://doi.org/10.1016/j.jalgebra.2020.11.007__Journal of Algebra 570 (2021): 164–214.https://doi.org/10.1016/j.jalgebra.2020.11.007 .