n-Widths of Hp-spaces in Lq(-1, 1). - Klaus Wilderotter (J. Complex., 1992)

The Fine Structure of the n-Widths of Hp-Spaces in Lq(-1, 1). - Klaus Wilderotter (J. Complex., 1995)

Optimal information for approximating periodic analytic functions. - Konstantin Yu. Osipenko; Klaus Wilderotter (Math. Comput., 1997)