1. Functions which are odd about several points;Boas, R. P., Jr.;Nieuw Arch. Wisk. (3),1953
2. Functions whose differences belong to a given class;de Bruijn, N. G.;Nieuw Arch. Wiskunde (2),1951
3. A difference property for Riemann integrable functions and for some similar classes of functions;de Bruijn, N. G.;Nederl. Akad. Wetensch. Proc. Ser. A. {\bf55} = Indagationes Math.,1952
4. T. Carleman, Les fonctions quasi-analytiques, Paris, 1926.
5. H. Cramér, Random variables and probability distributions, Cambridge, 1937.