@article{EJDE_1997__1997__a0,
     author = {Palagachev,  Dian K. and Popivanov,  Peter R.},
     title = {Sub-elliptic boundary value problems for quasilinear operators},
     journal = {Electronic journal of differential equations},
     year = {1997},
     volume = {1997},
     zbl = {0886.35061},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_1997__1997__a0/}
}