@article{10_4153_CMB_1986_052_5,
     author = {Cater, F. S.},
     title = {An {Elementary} {Proof} of a {Theorem} on {Unilateral} {Derivatives}},
     journal = {Canadian mathematical bulletin},
     pages = {341--343},
     year = {1986},
     volume = {29},
     number = {3},
     doi = {10.4153/CMB-1986-052-5},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1986-052-5/}
}