@techreport{BorndoerferGroetschelLoebel1998, author = {Ralf Bornd{\"o}rfer and Martin Gr{\"o}tschel and Andreas L{\"o}bel}, title = {Optimization of Transportation Systems}, institution = {ZIB}, address = {Takustr. 7, 14195 Berlin}, number = {SC-98-09}, language = {eng}, year = {1998} }