@article{NUMA_1974__23_132319,
     author = {J. Schr\"oder},
     title = {Upper and {Lower} {Bounds} for {Solutions} of {Generalized} {Two-Point} {Boundary} {Value} {Problems.}},
     journal = {Numerische Mathematik},
     pages = {433--457},
     publisher = {mathdoc},
     volume = {23},
     year = {1974},
     zbl = {0293.65058},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1974__23_132319/}
}