Comorbidities of primary headache disorders: a literature review with meta-analysis. - Caponnetto, Valeria; Deodato, Manuela; Robotti, Micaela; Koutsokera, Maria; Pozzilli, Valeria; Galati, Cristina; Nocera, Giovanna; De Matteis, Eleonora; De Vanna, Gioacchino; Fellini, Emanuela; Halili, Gleni; Martinelli, Daniele; et al. (Journal of Headache & Pain, 2021)