@article{weko_95623_1,
   author	 = "Kazuya,Haraguchi and Yasutaka,Abe and Akira,Maruoka",
   title	 = "How to Produce BlockSum Instances with Various Levels of Difficulty",
   journal	 = "Journal of information processing",
   year 	 = "2012",
   volume	 = "20",
   number	 = "3",
   pages	 = "727--737",
   month	 = "jul"
}