@article{NUMA_1959__1_131419,
     author = {L. COLLATZ and J. SCHR\"ODER},
     title = {Einschlie{\ss}en der {L\"osungen} von {Randwertaufgaben.}},
     journal = {Numerische Mathematik},
     pages = {61--72},
     publisher = {mathdoc},
     volume = {1},
     year = {1959},
     zbl = {0118.12301},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1959__1_131419/}
}