@article{RSMUP_1981__64__77_0,
     author = {Cannarsa, Piermarco},
     title = {On a maximum principle for elliptic systems with constant coefficients},
     journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova},
     pages = {77--84},
     publisher = {Seminario Matematico of the University of Padua},
     volume = {64},
     year = {1981},
     mrnumber = {636627},
     zbl = {0473.35016},
     language = {en},
     url = {http://www.numdam.org/item/RSMUP_1981__64__77_0/}
}