1. 1) H. Kobayashi : Kigyo Kenkyu ‘BHP Billiton’ (2005), (Metal Economics Research Institute, Japan)
2. 2) A. Shibata : BRICs and Energy Resources, Nov. (2005) (Marubeni Economic Report)
3. 3) IEA : Oil Market Report 7/13/(2005)
4. 4) Agency for Natural Resources and Energy : “Rare metals bichiku 7 kosyu no juyo no genjo ni-tsuite (kobetsu bunseki)” (2005)
5. 5) Reuters News Service, Sept.13 (1999)