@techreport{AehligMirandaOng04ax,
  author =   {Aehlig, Klaus and Miranda, Jolie G de and Ong, C H  Luke},
  title =    {Safety is not a restriction at level 2 for string languages},
  institution={Oxford University Computing Laboratory},
  type={Technical Report},
  number={PRG-RR-04-23},
  year =     {2004}}