@article{RSMUP_1979__61__361_0,
     author = {Bratti, Giuliano},
     title = {A link between global solvability and solvability over compacts for systems like : $(P(D_x, D_y) u = f, \ Qu = 0)$},
     journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova},
     pages = {361--364},
     publisher = {Seminario Matematico of the University of Padua},
     volume = {61},
     year = {1979},
     mrnumber = {569672},
     zbl = {0449.35066},
     language = {en},
     url = {http://www.numdam.org/item/RSMUP_1979__61__361_0/}
}