Andersen, N.B. 2000. Invariant fundamental solutions and solvability for $\mathrm{GL} (n, \mathsf{C})/U(p,q)$. MATHEMATICA SCANDINAVICA. 86, 1 (Mar. 2000), 143–160. DOI:https://doi.org/10.7146/math.scand.a-14286.