TY JOUR TI METHODOLOGICAL APPROACHES TO ESTIMATION OF EFFICIENCY OF REGIONAL AGRO-INDUSTRIAL COMPLEX FUNCTION OF VOLGA FEDERAL DISTRICT KW economic efficiency KW competitiveness KW economic potential KW regional efficiency KW innovative way of agribusiness development KW agriculture KW integral indicator. JO Vestnik of Kazan State Agrarian University AU Zaydullina, A.A. PY 2018 IS 13 PB Kazan state agrarian University