Progression of Parkinson's disease as evaluated by Hoehn and Yahr stage transition times

- Zhao, Yin Jiao; Wee, Hwee Lin; Chan, Yiong-Huak; Seah, Soo Hoon; Au, Wing Lok; Lau, Puay Ngoh; Pica, Emmanuel Camara; Li, Shu Chuen; Luo, Nan; Tan, Louis C. S.