RT Journal Article SR Electronic T1 Objective measures for the progression of Parkinson’s disease JF Journal of Neurology, Neurosurgery & Psychiatry JO J Neurol Neurosurg Psychiatry FD BMJ Publishing Group Ltd SP 287 OP 288 DO 10.1136/jnnp.74.3.287 VO 74 IS 3 A1 B Snow YR 2003 UL http://jnnp.bmj.com/content/74/3/287.1.abstract AB