TY JOUR TI INTEGRATED ASSESSMENT OF THE ECONOMIC EFFICIENCY OF AI AGENTS IN SALES AND MARKETING OF SMALL AND MEDIUM-SIZED ENTERPRISES KW AI agents KW artificial intelligence KW small and medium-sized enterprises KW economic efficiency KW sales KW marketing KW business process automation KW return on investment KW useful autonomy JO MOSCOW ECONOMIC JOURNAL AU Treschevskiy, D.Y. AU Kolyvanov, D.A. PY 2026 IS 11 PB Electronic science