1. Nonmotor fluctuations in Parkinson's disease: frequent and disabling;Witjas;Neurology,2002
2. Autonomic deficits in Parkinson's syndrome;Appenzeller;Arch Neurol,1971
3. Non-motor symptoms of Parkinson's disease;Dewey,2003
4. Autonomic complications of Parkinson's disease;Hiner,2000
5. Autonomic nervous system dysfunction in Parkinson's disease;Zesiewicz;Curr Treat Options Neurol,2003