Peter Junghanns is Professor Emeritus at the Mathematics Department of the Technical University of Chemnitz, Germany, where he got his habilitation in 1984. His field of specialization includes analysis and numerical methods for operator equations, in particular integral equations.Giuseppe Mastroianni is emeritus professor at the University of Basilicata (Italy) since 2013, where he had been full professor of Numerical Analysis since 1987. In 1971 he graduated in Mathematics at the University of Naples "Federico II", where he began his academic career. He is author of numerous papers on polynomial approximation, positive operators, mechanical quadrature and numerical treatment of integral equations as well as of the monographs "Interpolation processes. Basic theory and applications" (with G.V. Milovanovic) and "Elementi di teoria dell'approssimazione polinomiale" (with M.C. De Bonis and I. Notarangelo).Incoronata Notarangelo is assistant professor of Numerical Analysis at the University of Turin (Italy) since 2019. In 2010 she received a PhD in Mathematics from the University of Basilicata (Italy), in cooperation with the University of Szeged (Hungary). She is author of papers on polynomial approximation, quadrature rules and numerical methods for integral equations as well as of the monograph "Elementi di teoria dell'approssimazione polinomiale" (with M.C. De Bonis and G. Mastroianni).