On Teichmüller's modulus problem in $\mathsf{R}^n$.

M. Vuorinen, “On Teichmüller’s modulus problem in $\mathsf{R}^n$”., Math. Scand., vol. 63, pp. 315–333, Jun. 1988, doi: 10.7146/math.scand.a-12244.