1. Achiezer, N. I., “Vorlesungen liber Approximations-theorie”, Akademic Verlag, Berlin, 1953, translated as, “On the Theory of Approximation”, Ungar, New York, 1956. (Second German edition, Berlin, 1967.) “Elements of the Theory of Elliptic Functions”, 2nd edition (in Russian), 1970. For complete bibliographies of Achiezer see the articles on him in Uspehi Mat. Nauk ≡ Russian Math. Surveys, 16, 6, (102),1961; p. 14; 26,6, (162), 1971, pp. 257–261; 36; 4, (220), 1981, pp. 183–4.
2. Amer, R. A., Schwarz, H. R., “Contributions to the approximation problem of electrical filters”, Mitt. Inst. ang. Math., ETH, Zürich, #9, 1964.
3. Bateman Project, “Higher Transcendental Functions, II”, McGraw Hill, New York, 1953.
4. Bernstein, S., “Lecons sur les propriéteé exctrémales et la meilleure approximation des fonctions analytiques d’une variable réelle”, Gauthier-Villars, Paris, 1926. Chel., 1970.
5. Blum, E. K., “Numerical analysis and computation, theory and practice”, Addison-Wesley, 1972.