Krishnan A, Silver N (2009). Headache (chronic tension type), search date March 2007. Online version of BMJ Clinical Evidence: http://www.clinicalevidence.com.
Naumann M, et al. (2008). Assessment: Botulinum neurotoxin in the treatment of autonomic disorders and pain (an evidence-based review): Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Neurology, 70(19): 1707–1714.
Linde K, et al. (2009). Acupuncture for tension-type headache. Cochrane Database of Systematic Reviews (1).
Other Works Consulted
Ropper AH, Samuels MA (2009). Headache and other craniofacial pains. In Adams and Victor's Principles of Neurology, 9th ed., pp. 162–188. New York: McGraw-Hill.