Cleveland Clinic: "Understanding Headaches & Migraines."<br> Mayo Clinic: "Migraines: Are they triggered by weather?"<br>American Migraine Foundation: "Migraine in Women."<br><i>Journal of Headache Pain:</i> "Migraine in women: the role of hormones and their impact on vascular diseases."<br>American Migraine Foundation: "Headache 'Red Flags': When to See Your Doctor."