@proceedings{DBLP:conf/fm/1991-1,
  editor    = {S{\o}ren Prehn and
               W. J. Toetenel},
  title     = {VDM '91 - Formal Software Development, 4th International
               Symposium of VDM Europe, Noordwijkerhout, The Netherlands,
               October 21-25, 1991, Proceedings, Volume 1: Conference Contributions},
  booktitle = {VDM Europe (1)},
  publisher = {Springer},
  series    = {Lecture Notes in Computer Science},
  volume    = {551},
  year      = {1991},
  isbn      = {3-540-54834-3},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}