@article{weko_3857_1,
   author	 = "MATSUSAKA,Takahisa  and NISHIE,Hitonaru  and SHIMADA,Masaki  and KUTSUKAKE,Nobuyuki and ZAMMA,Koichiro  and NAKAMURA,Michio and NISHIDA,Toshisada ",
   title	 = "Tool-use for drinking water by immature chimpanzees of Mahale: Prevalence of an unessential behavior",
   journal	 = "Primates ",
   year 	 = "2006",
   volume	 = "47",
   number	 = "2",
   pages	 = "113--122",
   month	 = "apr"
}