@article{DJDHughes:PWS,
  author    =  {Hughes, Dominic J.D.},
  title     =  {Proofs {W}ithout {S}yntax},
  journal   =  {Annals of {M}athematics},
  year      =  {2006},
  month     =  {November},
  volume    =  {143},
  number    =  {3},
  pages     =  {1065--1076}
}