@article{AIF_2004__54_5_1443_0,
     author = {Bove, Antonio and Treves, Fran\c{c}ois},
     title = {On the {Gevrey} hypo-ellipticity of sums of squares of vector fields},
     journal = {Annales de l'Institut Fourier},
     pages = {1443--1475},
     publisher = {Association des Annales de l{\textquoteright}institut Fourier},
     volume = {54},
     number = {5},
     year = {2004},
     doi = {10.5802/aif.2055},
     zbl = {1073.35067},
     mrnumber = {2127854},
     language = {en},
     url = {https://aif.centre-mersenne.org/articles/10.5802/aif.2055/}
}