Alberto Ferrari, Alessandra Carobbio, Arianna Masciulli, Arianna Ghirardi, Guido Finazzi, Valerio De Stefano, Alessandro Maria Vannucchi, Tiziano Barbui. Clinical outcomes under hydroxyurea treatment in polycythemia vera: a systematic review and meta-analysis. Haematologica 2019;104(12):2391-2399; https://doi.org/10.3324/haematol.2019.221234.