@article{PMF_1896_7_1_a4,
     author = {Lie, Sophus and \.Zorawski, Kazimierz},
     title = {Przyczynek do og\'olnej teoryi r\'owna\'n r\'o\.zniczkowych cz\k{a}stkowych dowolnego rz\k{e}du},
     journal = {Prace Matematyczno-Fizyczne},
     pages = {69--136},
     publisher = {mathdoc},
     volume = {7},
     number = {1},
     year = {1896},
     language = {pl},
     url = {http://geodesic.mathdoc.fr/item/PMF_1896_7_1_a4/}
}