@InProceedings{alti:lics01,
  author =       "Thorsten Altenkirch and Peter Dybjer and Martin Hofmann and Phil Scott",
  title =        "Normalization by evaluation for typed lambda calculus with
coproducts",
  pages =        "303-310",
  booktitle =    "16th Annual IEEE Symposium on Logic in Computer
                  Science",
  year =         "2001"
}