TY  - JOUR
AU  - Cater, F. S.
TI  - An Elementary Proof of a Theorem on Unilateral Derivatives
JO  - Canadian mathematical bulletin
PY  - 1986
SP  - 341
EP  - 343
VL  - 29
IS  - 3
UR  - http://geodesic.mathdoc.fr/articles/10.4153/CMB-1986-052-5/
DO  - 10.4153/CMB-1986-052-5
ID  - 10_4153_CMB_1986_052_5
ER  -