Goldstein, P., and P. Hajlasz. “Modulus of Continuity of Orientation Preserving Approximately Differentiable Homeomorphisms With a.e. Negative Jacobian”. Annales Fennici Mathematici, vol. 43, no. 1, Feb. 2018, pp. 147-70, doi:10.5186/aasfm.2018.4333.