@article{ejors,
   Author =     {Martin Henz and Tobias M{\"u}ller and Sven Thiel},
   Title =      {Global Constraints for Round Robin Tournament Scheduling},
   journal =    {European Journal for Operational Research},
   year = 2004,
   month = feb,
   volume = 153,
   number = 1,
   pages = {92--101}
}