@article{10_14708_cm_v26i1_6155,
     author = {J. Popenda},
     title = {Finite difference inequalities},
     journal = {Commentationes Mathematicae},
     pages = { 89--96},
     year = {1986},
     volume = {26},
     number = {1},
     doi = {10.14708/cm.v26i1.6155},
     language = {pl},
     url = {http://geodesic.mathdoc.fr/articles/10.14708/cm.v26i1.6155/}
}