Salimov R. R., and Stefanchuk M. V. “Logarithmic Asymptotics of the Nonlinear Cauchy – Riemann – Beltrami Equation”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 73, no. 3, Mar. 2021, pp. 395 -07, doi:10.37863/umzh.v73i3.6403.