Colucci, M.E. et al. 2019. On field vaccine effectiveness in three periods of 2018/2019 influenza season in Emilia-Romagna Region. Acta Biomedica Atenei Parmensis. 90, 9-S (Sep. 2019), 21–27. DOI:https://doi.org/10.23750/abm.v90i9-S.8699.