1. N.I. Achieser,Theory of Approximation (Frederick Ungar Publ., New York, 1956).
2. N.I. Akhiezer,The Classical Moment Problem (Oliver and Boyd, Edinburgh 1969). Originally published Moscow (1961).
3. A. Bultheel and P. Dewilde, Orthogonal functions related to the Nevanlinna-Pick problem, in:Proc. 4th Int. Conf. on Mathematical Theory of Networks and Systems, Delft (Western Periodicals, North-Hollywood, 1979), pp. 207–212.
4. A. Bultheel, P. González-Vera, E. Hendriksen, and O. Njåstad, A Szegő theory for rational functions, Technical Report TW131, Computer Science Department, K.U. Leuven (May 1990).
5. A. Bultheel, P. González-Vera, E. Hendriksen, and O. Njåstad, Orthogonal rational functions similar to Szegő polynomials, IMACS 9 (1991) 195–204.