@article{ELMA_1988__43_3_141435,
     author = {Lawrence Zalcman},
     title = {Positive derivatives and increasing functions.},
     journal = {Elemente der Mathematik},
     pages = {120--121},
     publisher = {mathdoc},
     volume = {43},
     number = {3},
     year = {1988},
     zbl = {0701.26006},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1988__43_3_141435/}
}