@article{Copestake:00,
  author = {Copestake, Ann},
  title = {Definitions of Typed Feature Structures},
  journal = {Natural Language Engineering},
  editor = {Flickinger, Dan and Oepen, Stephan and 
            Tsujii, J. and Uszkoreit, Hans},
  volume = {6 (1) ({S}pecial Issue on Efficient Processing with {HPSG})},
  pages = {109$\,$--$\,$112},
  year = 2000
}