@article{Courtier_1994,
title={A strategy for operational implementation of 4D‐Var,
using an incremental approach},
volume={120},
ISSN={1477-870X},
url={http://dx.doi.org/10.1002/qj.49712051912},
DOI={10.1002/qj.49712051912},
number={519},
journal={Quarterly Journal of the Royal Meteorological Society},
publisher={Wiley},
author={Courtier,
P. and Thépaut,
J.‐N. and Hollingsworth,
A.},
year={1994},
month=jul,
pages={1367–1387} }