Ds. Lubinsky et V. Totik, BEST WEIGHTED POLYNOMIAL-APPROXIMATION VIA JACOBI-EXPANSIONS, SIAM journal on mathematical analysis, 25(2), 1994, pp. 555-570
Freud's method is modified to prove the Jackson-Favard estimate for we
ighted algebraic polynomials with Jacobi weights. This approach uses o
nly classical results from the theory of orthogonal polynomials.