@article{AIF_1976__26_2_35_0,
     author = {Unterberger, Andr\'e and Unterberger, Julianne},
     title = {H\"older estimates and hypoellipticity},
     journal = {Annales de l'Institut Fourier},
     pages = {35--54},
     publisher = {Institut Fourier},
     address = {Grenoble},
     volume = {26},
     number = {2},
     year = {1976},
     doi = {10.5802/aif.613},
     mrnumber = {54 #5611},
     zbl = {0318.35018},
     language = {en},
     url = {http://www.numdam.org/articles/10.5802/aif.613/}
}