@article{GroetschelPadberg1977, author = {Martin Gr{\"o}tschel and Manfred Padberg}, title = {Lineare Charakterisierungen von Travelling Salesman Problemen}, journal = {Zeitschrift f{\"u}r Operations Research, Series A}, volume = {21}, number = {1}, pages = {33 -- 64}, year = {1977}, }