\Bibitem{Puk79} \by S.~V.~Pukhov \paper Inequalities between the Kolmogorov and the Bernstein diameters in a Hilbert space \jour Mat. Zametki \yr 1979 \vol 25 \issue 4 \pages 619--628 \mathnet{http://mi.mathnet.ru/mzm10037} \mathscinet{http://mathscinet.ams.org/mathscinet-getitem?mr=534304} \zmath{https://zbmath.org/?q=an:0424.46017|0414.46016} \transl \jour Math. Notes \yr 1979 \vol 25 \issue 4 \pages 320--326 \crossref{https://doi.org/10.1007/BF01688487}