INCIDENCE AND CAUSES OF IRON DEFICIENCY AMONG PEOPLE OF SMALL ETHNIC GROUPS OF THE NORTH (KHANTY AND MANSI) RESIDING IN URBAN AREAS AND THOSE PRESERVING THEIR TRADITIONAL LIFESTYLE (RESIDING IN CAMPS AND VILLAGES): EXPERIENCE OF USING IRON SUPPLEMENTS Статья Solovyova A.V., Chegus L.A. Voprosy Ginekologii, Akusherstva i Perinatologii. Dynasty Publishing House. Том 20. 2021. С. 48-54