TY JOUR TI REVIEW OF THEORETICAL APPROACHES TO THE DEFINITION OF THE ESSENCE OF MARKETING AND MARKETING ACTIVITIES KW marketing KW marketing activities KW marketing practices KW marketing evolution KW classification of approaches KW the essence of marketing JO Trade, service, food industry AU Nikitin, V.V. AU Voloshin, A.V. PY 2022 IS 2 PB Siberian Federal University