@Misc{		  dixkum92,
  author	= {J\"{u}rgen Dix and Martin Kummer},
  title		= {{H}erbrand's {T}heorem for {N}onstandard {I}nference
		  {O}perations},
  howpublished	= {Logic Colloquium 1992, Veszprem, Hungaria},
  month		= {August},
  year		= {1992}
}