A. Silver

Singing in groups for Parkinson's disease (SING-PD): a pilot study of group singing therapy for PD-related voice/speech disorders.

V. Vanderhorst, D. Tarsy, L. Shih, 2012, Parkinsonism & related disorders.

A randomized clinical trial of high-dosage coenzyme Q10 in early Parkinson disease: no evidence of benefit.

Stephanie D. Wilson, S. Ellias, J. Nutt, 2014, JAMA neurology.