1. S. N. Mergelyan, “Uniform approximations of functions of a complex variable,”Uspekhi Mat. Nauk [Russian Math. Surveys],7, No. 2, 31–122 (1952).
2. J. J. Carmona, “Mergelyan approximation theorem for rational modules,”J. Approx. Th.,44, 113–126 (1985).
3. J. Verdera, “On the uniform approximation problem for the square of the Cauchy-Riemann operator,” Preprint Universitat Autonoma de Barcelona, No. 3 (1991).
4. T. Gamelin,Uniform Algebras, Prentice Hall, Englewood Cliffs (1969).
5. G. M. Goluzin,Geometric Theory of Functions of One Complex Variable [in Russian], Gostekhizdat, Moscow-Leningrad (1952).