1. V. T. Shevaldin, “A problem of extremal interpolation,” Math. Notes 29 (4), 310–320 (1981).
2. V. T. Shevaldin, “Some problems of extremal interpolation in the mean for linear differential operators,” Trudy Mat. Inst. Steklova 164, 203–240 (1983).
3. J. H. Ahlberg, E. N. Nilson, and J. L. Walsh, The Theory of Splines and Their Applications (Academic, New York, 1967; Mir, Moscow, 1972).
4. Yu. N. Subbotin, “On the relations between finite differences and the corresponding derivatives,” Proc. Steklov Inst. Math. 78, 23–42 (1965).
5. C. A. Micchelli, “Cardinal L-splines,” in Studies in Splines and Approximation Theory (Academic, New-York, 1976), pp. 203–250.