@Article{Kahl-2002a,
  author = {Wolfram Kahl},
  title = {Refinement and Development of Programs from Relational Specifications},
  journal = ENTCS,
  year = 2003,
  volume = 44,
  number = 3,
  pages = {51--93},
  DOI = {10.1016/S1571-0661(04)80932-0},
  DOIURL = {http://dx.doi.org/10.1016/S1571-0661(04)80932-0},
  abstract = {These tutorial notes present an overview
                  of specification and refinement concepts and methods
                  that are based on relations.},
}