@article{BeckertSchlager05, 
   title         = {Refinement and Retrenchment for Programming Language Data Types},
   author        = {Bernhard Beckert and Steffen Schlager},
   journal       = {Formal Aspects of Computing},  
   volume        = {17},
   number        = {4},
   pages         = {423--442},
   year          = {2005}, 
   publisher     = {Springer}
}