@phdthesis{74189,
  author = {J.C. Derber and D.F. Parrish and J.G. Sela},
  title = {The SSI analysis system and extensions to 4D},
  year = {1992},
  journal = {Workshop on Variational Assimilation, with special emphasis on Three-dimensional Aspects, 9-12 November 1992},
  pages = {15-36},
  month = {1992},
  publisher = {ECMWF},
  address = {Shinfield Park, Reading},
  language = {eng},
}