Vakarchuk, S.B. 2014. Jackson-Type Inequalities for the Special Moduli of Continuity on the Entire Real Axis and the Exact Values of Mean $ν$ - Widths for the Classes of Functions in the Space $L_2 (ℝ)$. Ukrains’kyi Matematychnyi Zhurnal. 66, 6 (Jun. 2014), 740–766.