@article{10_4064_ap_29_3_215_228,
     author = {Z. Kamont and W. Pawelski},
     title = {On the characteristics for a system of partial differential equations of the first order in a special case},
     journal = {Annales Polonici Mathematici},
     pages = {215--228},
     publisher = {mathdoc},
     volume = {29},
     number = {3},
     year = {1974},
     doi = {10.4064/ap-29-3-215-228},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap-29-3-215-228/}
}