Gal, Sorin, and Ionut Iancu. “Quantitative Approximation by Nonlinear Angheluta-Choquet Singular Integrals”. J. Numer. Anal. Approx. Theory, vol. 49, no. 1, Sept. 2020, pp. 54-65, https://doi.org/10.33993/jnaat491-1217.