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@article{PORMA_1968__27_3_115071, author = {Lai, Hon-Fei}, title = {On piecewise-constant functions}, journal = {Portugaliae mathematica}, pages = {161--168}, publisher = {mathdoc}, volume = {27}, number = {3}, year = {1968}, mrnumber = {0270347}, zbl = {0198.27301}, language = {en}, url = {http://geodesic.mathdoc.fr/item/PORMA_1968__27_3_115071/} }
Lai, Hon-Fei. On piecewise-constant functions. Portugaliae mathematica, Tome 27 (1968) no. 3, pp. 161-168. http://geodesic.mathdoc.fr/item/PORMA_1968__27_3_115071/