@TechReport{ Griebel.Scherer.Schweitzer:2004, author = {M.~Griebel and K.~Scherer and M.~A.~Schweitzer}, title = {Robust Norm Equivalencies and Optimal Preconditioners for Diffusion Problems}, institution = {Sonderforschungsbereich 611, Universit\"at Bonn}, year = {2004}, optkey = {}, type = {Preprint}, number = {154}, optaddress = {}, optmonth = {}, pdf = {http://wissrech.ins.uni-bonn.de/research/pub/schweitz/robustmg.pdf} , annote = {report,C2} }