1. Faculty of Economics; Niigata University; 8050 Ikarashi 2-no-cho Nishi-ku, Niigata, Niigata Japan
2. Faculty of Economics; Tohoku Gakuin University; 1-3-1 Tsuchitoi Aoba-ku, Sendai Miyagi Japan
3. Graduate School of Economics; Nagoya University; Furo-cho Chikusa-ku, Nagoya Aichi Japan