1. Neurology; Harvard Medical School; Boston MA USA
2. John R. Graham Headache Center; Brigham & Women's Faulkner Hospital; Boston MA USA
3. Department of Geography; Texas A&M University; College Station TX USA
4. Headache Service; Neurology and Neurotherapeutics and Ophthalmology; University of Texas Southwestern; Dallas TX USA
5. Division of Headache and Pain; Department of Neurology; Brigham & Women's Faulkner Hospital; Boston MA USA