Szegő's theorem for matrix orthogonal polynomials. - Maxim S. Derevyagin; Olga Holtz; Sergey Khrushchev; Mikhail Tyaglov (J. Approx. Theory, 2012)

Mergelyan's theorem for zero free functions. - Sergey Khrushchev (J. Approx. Theory, 2013)

A continuous function with universal Fourier series on a given closed set of Lebesgue measure zero. - Sergey Khrushchev (J. Approx. Theory, 2020)

Uniformly convergent Fourier series with universal power parts on closed subsets of measure zero. - Sergey Khrushchev (J. Approx. Theory, 2023)