@article{Kelfve2013,
author = {Kelfve, S. and Thorslund, M. and Lennartsson, C.},
title= {Sampling and non-response bias on health-outcomes in surveys of the oldest old},
year = {2013},
doi = {10.1007/s10433-013-0275-7},
volume = {10},
number = {3},
pages = {237--245},
}