@article{JRAM_1955__194_150290,
     author = {L. Collatz},
     title = {\"Uber monotone {Systeme} linearer {Ungleichungen.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {193--194},
     publisher = {mathdoc},
     volume = {194},
     year = {1955},
     zbl = {0066.26602},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1955__194_150290/}
}