RT Journal Article SR Electronic T1 Hermann von Helmholtz (1821–94) JF Journal of Neurology, Neurosurgery & Psychiatry JO J Neurol Neurosurg Psychiatry FD BMJ Publishing Group Ltd SP 766 OP 766 DO 10.1136/jnnp.65.5.766 VO 65 IS 5 A1 L F HAAS YR 1998 UL http://jnnp.bmj.com/content/65/5/766.abstract AB