3Bischoff-Ferrari H A,Stahelin H B,Dick W,et al.Effects of vitamin dand calcium supplementation on falls:A randomized controlled trial[J].J Bone Miner Res,2003,18(2):343-351.
4Butler R N,Davis R,Lewis C B,et al.Physical fitness:Benefits of exercise for older patients[J].Geriatrics,1998,53(10):46,49-52,61-62.