@article{Beckett 1996,
author = {Beckett , L. and Brock, D. and Lemke, J.H. and Mendes de Leon, C.F. and Guralnik, J.M. and Fillenbaum, G.G. and Branch, L.G. and Wetle, T.T. and Evans, D.A.},
title= {Analysis of change in self-reported physical function among older persons in four population studies},
year = {1996},
journal = {American Journal of Epidemiology},
volume = {143},
number = {8},
pages = {766--778},
}