A discrete integral representation for polynomials of fixed maximal degree and their universal Korovkin closure. Michael Pannenberg — 1986 Journal für die reine und angewandte Mathematik
Stable rank of Fourier algebras and an application to Korovkin theory. Michael Pannenberg — 1990 Mathematica Scandinavica
A Characterization of a Class of Locally Compact Abelian Groups via Korovkin Theory. Michael Pannenberg — 1990 Mathematische Zeitschrift