Key references: Cluster headache

Becker WJ. Cluster headache: conventional pharmacological management. Headache 2013;53(7):1191–6. https://www.ncbi.nlm.nih.gov/pubmed/23773141
Goadsby PJ, Cittadini E, Cohen AS. Trigeminal autonomic cephalalgias: paroxysmal hemicrania, SUNCT/SUNA, and hemicrania continua. Semin Neurol 2010;30(2):186–91. https://www.ncbi.nlm.nih.gov/pubmed/20352588
Koppen H, Stolwijk J, Wilms EB, Driel V, Ferrari MD, Haan J. Cardiac monitoring of high-dose verapamil in cluster headache: An international Delphi study. Cephalalgia 2016;36(14):1385–8. https://www.ncbi.nlm.nih.gov/pubmed/26868817
Newman LC. Trigeminal autonomic cephalalgias. Continuum (Minneap Minn) 2015;21(4 Headache):1041–57. https://www.ncbi.nlm.nih.gov/pubmed/26252590