@Unpublished{alti:f97,
  author = 	 {Thorsten Altenkirch and Martin Hofmann and Thomas Streicher},
  title = 	 {Reduction-free normalisation for system {$F$}},
  note = 	 {available from {\tt http://www.cs.nott.ac.uk/\~{}txa/publ/f97.pdf}},
  year =	 {1997},
  www = 	 {http://www.cs.nott.ac.uk/~txa/publ/f97.pdf},
}