Gal, Sorin, and Ionut Iancu. “Quantitative Approximation by Nonlinear Angheluta-Choquet Singular Integrals”. J. Numer. Anal. Approx. Theory 49, no. 1 (September 8, 2020): 54–65. Accessed November 8, 2025. https://www.ictp.acad.ro/jnaat/journal/article/view/1217.