@Book{Henz:1997_1,
      AUTHOR = {Henz, Martin},
      TITLE = {Objects for Concurrent Constraint Programming},
      YEAR = {1997},
      VOLUME = {426},
      SERIES = {The Kluwer International Series in Engineering and Computer Science},
      ADDRESS = {Boston},
      PUBLISHER = {Kluwer Acdemic Publishers},
      URL = {ftp://ftp.ps.uni-sb.de/pub/papers/ProgrammingSysLab/Diss-Henz.ps.gz},
      ANNOTE = {COLIURL : Henz:1997:OCC.pdf Henz:1997:OCC.ps}
}