@INPROCEEDINGS{Erletal01,
  AUTHOR =       {T. Erlebach and M. Gantenbein and D. Huerlimann and G. Neyer and A. Pagourtzis and P. Penna and K. Schlude and K. Steinhoefel and D. S. Taylor and P. Widmayer},
  TITLE =        {On the Complexity of Train Assignment Problems},
  BOOKTITLE =    {Proc. of the 12th International Symposium on Algorithms and Computation (ISAAC)},
  YEAR =         {2001},
  series =       {LNCS},
  volume =       {2223},
  pages =        {390-402}
}