@ARTICLE{AUROUX-05-CRAS,
 author = {Auroux, D. and Blum, J.},
 title = {Back and forth nudging algorithm for data assimilation problems},
 journal = {C. R. Acad. Sci. Paris, Ser. I},
 volume = {340},
 year = {2005},
 pages = {873--878},
}