Archbold, Robert J., and Eberhard Kaniuth. “On the Stable Rank and Real Rank of Group $C^*$-Algebras of Nilpotent Locally Compact Groups”. Mathematica Scandinavica 97, no. 1 (September 1, 2005): 89–103. Accessed July 25, 2026. https://journals.msp.org/mscand/article/view/732.