@article{De Vries2011,
author = {De Vries, N.M. and Staal, J.B. and Van Ravensberg, C.D. and Hobbelen, J.S.M. and Rikkert, M.O. and Sanden, M.},
title= {Outcome instruments to measure frailty: A systematic review},
year = {2011},
doi = {10.1016/j.arr.2010.09.001},
volume = {10},
number = {1},
pages = {104--114},
}