1. J. L. Walsh, The convergence of rational functions of best approximation, Mathematische Annalen 155 (1964), p. 252–264.
2. — The convergence of sequences of rational functions of best approximation with some free poles, Proceedings of General Motors Symposium of Approximation, September 1964, edited by H. L. Garabedian, published by Elsevier (Amsterdam), 1965, p. 1–16.
3. — Interpolation and approximation, American Mathematical Society Colloquium Publications 20 (1935).