Chinese herbal medicine treatment based on subgroup differentiation as adjunct therapy for Parkinson’s disease: study protocol of a pilot add-on, randomised, controlled, pragmatic... oleh Sam Chun Sum Yuen, Ka Kit Chua, Linda L. D. Zhong, Kam Wa Chan, Conrad Kwan Ho Chan, Kam Leung Chan, Zhixiu Lin, Vincent Mok, Alexander Y. Lau, Min Li