@techreport{GroetschelMartinWeismantel1992, author = {Martin Gr{\"o}tschel and Alexander Martin and Robert Weismantel}, title = {Routing in Grid Graphs by Cutting Planes.}, institution = {ZIB}, address = {Takustr. 7, 14195 Berlin}, number = {SC-92-26}, language = {eng}, year = {1992} }