@article{MZ_1972__127_171768,
     author = {Ray Redheffer and Roger Dell},
     title = {Sharp {Lower} {Bounds} for {Solutions} on {Nonlinear} {Differential} {Inequalities.}},
     journal = {Mathematische Zeitschrift},
     pages = {199--216},
     publisher = {mathdoc},
     volume = {127},
     year = {1972},
     zbl = {0223.35041},
     url = {http://geodesic.mathdoc.fr/item/MZ_1972__127_171768/}
}