@article{361707,
      url = {http://digitallibrary.un.org/record/361707},
      title = {Duration calculi : an overview},
      publisher = {UN University :},
      recid = {361707},
      pages = {i, 12 p.},
      address = {Tokyo :. 1993-06},
      year = {1993},
      month = {Jun},
}