1. Hille, E.: Analytic Function Theory, Vol. 1. New York: Ginn and Co. 1959.
2. Kelley, J. L.: General Topology. Princeton: van Nostrand 1960.
3. Lavrentieff, M.: Zur Theorie der konformen Abbildungen. Travaux de l'Institut Physico-mathématique Stekloff Leningrad 5, 159–245 (1934).
4. Mergelyan, S. N.: On the representation of functions by series of polynomials on closed sets. Dokl. Akad. Nauk SSSR (N.S.) 78, 405–408 (1951); Amer. Math. Soc. Transl. 85 (1953).
5. Mikusinski, J. G.: Operational Calculus. Warsaw 1959.