1. Abington Neurological Associates, Ltd., Abington, PA, USA
2. AbbVie Inc., Madison, NJ, USA
3. New England Institute for Neurology & Headache, Stamford, CT, USA
4. DENT Neurologic Institute, Amherst, NY, USA
5. Diamond Headache Clinic, Chicago, IL, USA
6. Jefferson Headache Center, Department of Neurology, Thomas Jefferson University, Philadelphia, PA, USA