Graded mesh refinement and error estimates of higher order for DGFE solutions of elliptic boundary value problems in polygons. Numerical Methods for Partial Differential Equations, (28)4:1124--1151, Wiley Subscription Services, Inc., A Wiley Company, 2012. [PUMA: Galerkin Sobolev Sobolev--Slobodetskii boundary discontinuous elliptic graded mesh method, problems, refinement, spaces spaces, value vorlaeufig weighted] URL