@Article{	  dixkum93a,
  author	= {J\"{u}rgen Dix and Martin Kummer},
  title		= {{H}erbrand's {T}heorem for {N}onstandard {I}nference
		  {O}perations (Abstract)},
  journal	= {Journal of Symbolic Logic},
  year		= {1993},
  volume	= {58},
  pages		= {1116--1117}
}