@incollection{Witt2005,
  author    = {Andreas Witt},
  title     = {Multiple hierarchies : new aspects of an old solution},
  booktitle = {Heterogeneity in focus: creating and using linguistic databases / Dipper, Stefanie, M. G{\"o}tze and M. Stede (eds.) ; Working Papers of the SFB 632, Interdisciplinary studies on information structure ; Vol. 2},
  isbn      = {978-3-937786-48-3},
  url       = {http://www.sfb632.uni-potsdam.de/publications/isis02_4witt.pdf},
  year      = {2005},
}