RT Journal Article SR Electronic T1 Changes of inherent muscle stiffness in Parkinson's disease. JF Journal of Neurology, Neurosurgery & Psychiatry JO J Neurol Neurosurg Psychiatry FD BMJ Publishing Group Ltd SP 944 DO 10.1136/jnnp.50.7.944 VO 50 IS 7 A1 V Dietz YR 1987 UL http://jnnp.bmj.com/content/50/7/944.1.abstract AB