@TECHREPORT{GBC05-filters-TR,
   AUTHOR       = {Anurag Garg and Roberto Battiti and Roberto G. Cascella},
   INSTITUTION  = {University of Trento},
   TITLE        = {``May I borrow Your Filter?'' Exchanging Filters to 
      Combat Spam in a Community},
   YEAR         = {2005},
   MONTH     = {November},
   NUMBER       = {DIT-05-089},
   TYPE         = {Technical Report},
}