@techreport{Amati&92,
		author       = " G.~Amati and  S.~Kerpedjiev ", 
		title	     = " An {I}nformation {R}etrieval {M}odel:  implementation and experiments", 
		institution  = " FUB 5B04892", 
		publisher    = "Fondazione Ugo Bordoni",
		address	     = "Roma", 
		year 	     = 1992,
}