@misc{73786,
  author = {F. Bouttier},
  title = {The development of 12-hourly 4D-Var. With annexes supplied by M. Miller, M. Hortal and L. Isaksen.},
  year = {2001},
  journal = {ECMWF Technical Memoranda},
  number = {348},
  pages = {21},
  month = {09/2001},
  publisher = {ECMWF},
  address = {Shinfield Park, Reading},
  url = {https://www.ecmwf.int/node/8344},
  doi = {10.21957/1whgd5xrr},
  language = {eng},
}