@misc{76780,
  author = {P. Undén and G.A. Kelly and D. Le Meur and L. Isaksen},
  title = {Observing system experiments with the 3D-Var assimilation system},
  year = {1997},
  journal = {ECMWF Technical Memoranda},
  number = {244},
  pages = {32},
  month = {12/1997},
  publisher = {ECMWF},
  address = {Shinfield Park, Reading},
  url = {https://www.ecmwf.int/node/12870},
  doi = {10.21957/2rglefpmo},
  language = {eng},
}