TY JOUR TI Circular transformation of the vegetable sector in the Kostanay region as a basis for effective development of the agricultural market KW circular closed-loop integration KW material costs KW correlation and regression analysis KW substandard vegetables JO INTERNATIONAL AGRICULTURAL JOURNAL AU Lysenko, M.V. AU Polyanskaya, O.A. AU Lysenko, Y.V. AU Korneev, D.N. AU Koshevaya, L.I. AU Kamdina, L.V. PY 2026 IS PB Electronic science