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@article{ELMA_1989__44_3_141460, author = {David E. Dobbs}, title = {A characterization of the tangent function.}, journal = {Elemente der Mathematik}, pages = {101--104}, publisher = {mathdoc}, volume = {44}, number = {3}, year = {1989}, zbl = {0706.26006}, url = {http://geodesic.mathdoc.fr/item/ELMA_1989__44_3_141460/} }
David E. Dobbs. A characterization of the tangent function.. Elemente der Mathematik, Tome 44 (1989) no. 3, pp. 101-104. http://geodesic.mathdoc.fr/item/ELMA_1989__44_3_141460/