@article{10_4064_ap78_3_6,
     author = {M. Langenbruch},
     title = {Laurent series expansion
for solutions of hypoelliptic
equations},
     journal = {Annales Polonici Mathematici},
     pages = {277--289},
     publisher = {mathdoc},
     volume = {78},
     number = {3},
     year = {2002},
     doi = {10.4064/ap78-3-6},
     language = {fr},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap78-3-6/}
}