@Unpublished{DJDHughes:hybrid,
  author    =  {Hughes, Dominic J.D.},
  title     =  {A classical sequent calculus free of structural rules},
  year      =  {2005},
  month     =  {June},
  note      =  {Submitted.  Archived as math.LO/0506463 at arXiv.org.}
}