Analysis of a non-standard finite element method based on boundary integral operators. Hofreither, Clemens; Langer, Ulrich; Pechstein, Clemens — 2010 ETNA. Electronic Transactions on Numerical Analysis [electronic only]
Zur numerischen Lösung des ersten biharmonischen Randwertproblems. Ulrich Langer Numerische Mathematik
A fast solver for the first biharmonic boundary value problem. Ulrich Langer; Dieter Bahlmann — 1992 Numerische Mathematik