@misc{74044,
  author = {P. Courtier and Erik Andersson and W.A. Heckley and J. Pailleux and Drasko Vasiljevic and M. Hamrud and A. Hollingsworth and Florence Rabier and Mike Fisher},
  title = {The ECMWF implementation of three dimensional variational assimilation. Part 1:Formulation},
  year = {1998},
  journal = {ECMWF Technical Memoranda},
  number = {241},
  pages = {30},
  month = {01/1998},
  publisher = {ECMWF},
  address = {Shinfield Park, Reading},
  url = {https://www.ecmwf.int/node/8787},
  doi = {10.21957/unhecz1kq},
  language = {eng},
}