1. Revishvili AS, Olovyanny VE, Sazhin VP, Anishenko MA, Kuznetcov AV, Mironova NL, Shelina NV. Surgical treatment in Russian Federation. Information and analytical collection for 2020. (In Russ.). https://anyflip.com/nvzse/qjoj/
2. Russian society of surgeons. Perforated ulcer. Clinical guidelines of Ministry of Health of Russian Federation. 2021:1-54. (In Russ.). https://cr.minzdrav.gov.ru/recomend/328_2
3. Acute peritonitis. Clinical guidelines. (In Russ.). https://www.mrckb.ru/files/ostryj-peritonit.pdf
4. A new method of classifying prognostic comorbidity in longitudinal studies: Development and validation
5. Classification of Surgical Complications