@techreport{weko_77148_1,
   author	 = "Taisuke,Izumi and Tomoko,Izumi and Hirotaka,Ono and Koichi,Wada",
   title	 = "Complexity of Minimum Certificate Dispersal Problem with Tree Structure",
   year 	 = "2011",
   institution	 = "Nagoya Institute of Technology, Ritsumeikan University, Kyushu University, Nagoya Institute of Technology",
   number	 = "3",
   month	 = "aug"
}