@article{10_4064_cm_41_2_257_263,
     author = {R. Fleissner and R. J. O'Malley},
     title = {Conditions implying the summability of approximate derivatives},
     journal = {Colloquium Mathematicum},
     pages = {257--263},
     publisher = {mathdoc},
     volume = {41},
     number = {2},
     year = {1979},
     doi = {10.4064/cm-41-2-257-263},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-41-2-257-263/}
}