@article{Remschmidt2015,
author = {Remschmidt, C. and Wichmann, O. and Harder, T.},
title= {Frequency and impact of confounding by indication and healthy vaccinee bias in observational studies assessing influenza vaccine effectiveness: a systematic review},
year = {2015},
doi = {10.1186/s12879-015-1154-y},
URL = {https://doi.org/10.1186/s12879-015-1154-y},
volume = {15},
number = {429},
}