Mortini, R., & Rupp, R. (2011). Approximation by invertible elements and the generalized $E$-stable rank for $A({\boldsymbol D})_{\mathsf R}$ and $C({\boldsymbol D})_{\mathrm{sym}}$. MATHEMATICA SCANDINAVICA, 109(1), 114–132. https://doi.org/10.7146/math.scand.a-15180