1. M. M. Dzhrbashyan, “Biorthogonal systems of rational functions and the best approximation of a Cauchy kernel on the real axis,” Mat. Sborn., 94, No. 3, 418–444 (1974).
2. S. Takenaka, “On the orthogonal functions and a new formula of interpolation,” Jap. J. Math., 2, 129–145 (1925).
3. F. Malmquist, “Sur la détermination d’une classe de fonctions analytiques par leurs valeurs dans un ensemble donné de points,” in: Comptes rendus du sixiene congres des mathematiciens scandinares, Copenhagen, (1926), pp. 253–259.
4. V. V. Savchuk and S. O. Chaichenko, “The best approximations of a Cauchy kernel on the real axis,” Ukr. Mat. Zh., 66, No. 11, 1540–1549 (2014).
5. H. Kober, “A note on approximation by rational functions,” Proc. of Edinburg Math. Soc., 7, No. 3, 123–133 (1944).