@article{10_14708_cm_v21i2_5992,
     author = {M. Kierla\'nczyk},
     title = {On a differential inequality of the type {\(X''} + {f(t)X} \geq 0\)},
     journal = {Commentationes Mathematicae},
     pages = { 325--326},
     publisher = {mathdoc},
     volume = {21},
     number = {2},
     year = {1979},
     doi = {10.14708/cm.v21i2.5992},
     language = {pl},
     url = {http://geodesic.mathdoc.fr/articles/10.14708/cm.v21i2.5992/}
}