GÄ…siorowska , A. (2021). The gastrointestinal tract and COVID-19. Observations after the year of the pandemic. Part 1. Patients with diseases of the upper gastrointestinal tract. Medycyna Faktow (J EBM), 14(3(52), 225-231. https://doi.org/10.24292/01.MF.0321.2