N. G. Gravirovska and ZalyubovskаО. I., “REGIONAL PECULIARITIES OF DUODENUM PEPTIC ULCER PREVALENCE INDEXES AND TENDENCY OF THEIR DEVELOPMENT IN KHARKOV AND DNEPROPETROVSK REGIONS”, J. V. N. Karazin Khark. Nat. Univ., Ser. Med., no. 21, pp. 37-42, 1.