Neck pain disability is related to the frequency of migraine attacks: a cross-sectional study - Florencio, Lidiane L.; Chaves, Thaís Cristina; Carvalho, Gabriela F.; Gonçalves, Maria C.; Casemiro, Elisangela C. B.; Dach, Fabíola; Bigal, Marcelo E.; Bevilaqua-Grossi, Débora (Headache, 2014)