8Tang Z, Wang HX, Meng C, et al. The prevalence of functional disabihty in activities of daily living and instrumental activities of daily living among elderly Beijing Chinese. Arch Gerontol Get,1999,29:115-125.
9Meng C, Tang Z. Cognitive change and its predictive value among elderly people in Beijing. Korean J Res Gerontol, 1999,8:91-103.