1. V. K. Dzyadyk, ?Approximation method for approximating by algebraic polynomials the solutions of linear differential equations,? Izv. Akad. Nauk SSSR, Ser. Mat.,38, No. 4, 937?967 (1974).
2. V. K. Dzyadyk and L. A. Ostrovetskii, ?Approximating polynomials for solutions of boundary problems for ordinary linear differential equations,? Preprint. Inst. Mat. Akad. Nauk UkrSSR; 85.11.
3. V. K. Dzyadyk, ?On a problem of Chebyshev and Markov,? Anal. Math.,3, No. 3, 171?175 (1977).