@article{AIHPC_2018__35_2_327_0,
     author = {Dacorogna, B. and Gangbo, W. and Kneuss, O.},
     title = {Symplectic factorization, {Darboux} theorem and ellipticity},
     journal = {Annales de l'I.H.P. Analyse non lin\'eaire},
     pages = {327--356},
     publisher = {Elsevier},
     volume = {35},
     number = {2},
     year = {2018},
     doi = {10.1016/j.anihpc.2017.04.005},
     mrnumber = {3765545},
     zbl = {1476.58037},
     language = {en},
     url = {http://archive.numdam.org/articles/10.1016/j.anihpc.2017.04.005/}
}