@article{10_4064_ap_7_3_255_258,
     author = {A. Pli\'s},
     title = {On the uniqueness of the non-negative solution of the homogeneous mixed problem for a system of partial differential equations},
     journal = {Annales Polonici Mathematici},
     pages = {255--258},
     publisher = {mathdoc},
     volume = {7},
     number = {3},
     year = {1959},
     doi = {10.4064/ap-7-3-255-258},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap-7-3-255-258/}
}