@Article{         BarHillelPerlesShamir61Formal,
  Author        = "Bar-Hillel, Yehoshua and Perles, Micha A. and Shamir, Eli",
  citeulike-article-id="9539916",
  date-added    = "2013-12-18 15:49:37 +0000",
  date-modified = "2013-12-23 09:39:07 +0000",
  Journal       = {Zeitschrift f\"{u}r Phonetik, Sprachwissenschaft und Kommunikationsforschung},
  Keywords      = "classic and no pdf",
  Number        = "14",
  Pages         = "143--172",
  posted-at     = "2011-07-12 23:52:14",
  priority      = "2",
  Title         = "{On formal properties of simple phrase structure grammars}",
  Year          = "1961"
}

@Article{ BarHillelPerlesShamir61Formal, Author = "Bar-Hillel, Yehoshua and Perles, Micha A. and Shamir, Eli", citeulike-article-id="9539916", date-added = "2013-12-18 15:49:37 +0000", date-modified = "2013-12-23 09:39:07 +0000", Journal = {Zeitschrift f\"{u}r Phonetik, Sprachwissenschaft und Kommunikationsforschung}, Keywords = "classic and no pdf", Number = "14", Pages = "143--172", posted-at = "2011-07-12 23:52:14", priority = "2", Title = "{On formal properties of simple phrase structure grammars}", Year = "1961" }