@Article{J6,
  key    =       {J06},
  author = 	 {Christoph Benzm{\"u}ller and  Chad Brown and Michael Kohlhase},
  title = 	 {Higher-Order Semantics and Extensionality},
  journal = 	 {Journal of Symbolic Logic},
  year = 	 2004,
  volume =       69,
  number =        4,
  pages =        {1027-1088},
}