@article{10_4064_ap_26_1_61_71,
     author = {Tadeusz Rumak},
     title = {Estimation of functions by means of the first order partial differential inequalities},
     journal = {Annales Polonici Mathematici},
     pages = {61--71},
     publisher = {mathdoc},
     volume = {26},
     number = {1},
     year = {1972},
     doi = {10.4064/ap-26-1-61-71},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap-26-1-61-71/}
}