Bernard SL, Kincade JE, Konrad TR, Arcury TA, Rabiner DJ, Woomert A, DeFriese GH, Ory MG. Predicting mortality from community surveys of older adults: the importance of self-rated functional ability. J Gerontol B Psychol Sci Soc Sci. 1997 May; 52(3):S155-63.