@Article{Beckert:FAC-17-4-423,
  author =       "Bernhard Beckert and Steffen Schlager",
  title =        "Refinement and Retrenchment for Programming Language
                 Data Types",
  journal =      "Formal Aspects of Computing",
  volume =       "17",
  number =       "4",
  year =         "2005",
  pages =        "423--442",
  ee =           "http://dx.doi.org/10.1007/s00165-005-0073-x",
  URL =          "http://www.uni-koblenz.de/~beckert/pub/facj05.pdf",
}