@techreport{BorndoerferGroetschelJaeger2009, author = {Ralf Bornd{\"o}rfer and Martin Gr{\"o}tschel and Ulrich Jaeger}, title = {Planning Problems in Public Transit}, institution = {ZIB}, address = {Takustr. 7, 14195 Berlin}, number = {09-13}, language = {eng}, year = {2009} }