A set function without σ -additive extension having finitely additive extensions arbitrarily close to σ -additivity Jörn Lembcke — 1980 Czechoslovak Mathematical Journal
On infinitely many solutions of a semilinear elliptic eigenvalue problem Jörn Lembcke — 1989 Commentationes Mathematicae Universitatis Carolinae
Extension of linear forms with strict domination on locally compact cones. Jörn Lembcke; Bernd Anger — 1980 Mathematica Scandinavica