[1] Univ Calif Berkeley, Dept Agr & Resource Econ, 303 Giannini Hall, Berkeley, CA 94720 USA
[2] Czech Univ Life Sci Prague, Fac Econ & Management, Dept Trade & Finance, Kamycka 129, Prague 16500 6, Czech Republic
[3] North Caucasus Fed Univ, Dept Finance & Credit, Pushkin Str 1, Stavropol 355017, Russia
[4] Volga State Univ Technol, Dept Foreign Language & Linguist, Dept Management & Law, Lenin Sq 3, Yoshkar Ola 424000, Russia
[5] Prague Business Sch, Ctr Energy Studies, Werichova 29, Prague 15200, Czech Republic
[6] Tambov State Univ, Dept Econ & Management, Int Str 33, Tambov 392000, Russia