“On Field Vaccine Effectiveness in Three Periods of 2018 2019 Influenza Season in Emilia-Romagna Region”. Acta Biomedica Atenei Parmensis 90, no. 9-S (September 13, 2019): 21–27. Accessed June 30, 2024. https://mattioli1885journals.com/index.php/actabiomedica/article/view/8699.