RT Journal Article SR Electronic T1 An evolving headache JF Practical Neurology JO Pract Neurol FD BMJ Publishing Group Ltd SP 62 OP 65 DO 10.1136/jnnp.2007.140970 VO 8 IS 1 A1 Simpson, M A1 Duncan, C A1 Knight, R A1 Strachan, M W J YR 2008 UL http://pn.bmj.com/content/8/1/62.abstract AB