A note on geometric characterization of Fréchet differentiability.
(English).Commentationes Mathematicae Universitatis Carolinae,
vol. 17
(1976),
issue 1,
pp. 195-204
[1] J. DURDIL: On the geometric characterization of differentiability I. Comment. Math. Univ. Carolinae 15 (1974), 521-540. MR 0426019 | Zbl 0289.58004
[2] E. L. ROETMAN: Tangent planes and differentiation. Math. Mag. 43 (1970), 1-7. MR 0257290 | Zbl 0193.01501
[3] K. YOSIDA: Functional Analysis. Springer-Verlag, 1965. Zbl 0126.11504