@article{GDZPPN002028573, title = {On an Exponential-Cosine Operator-Valued Functional Equation. (Short Communication).}, journal = {Aequationes mathematicae}, volume = {13}, year = {1975}, pages = {117-117}, zbl = {0334.39002}, url = {http://dml.mathdoc.fr/item/GDZPPN002028573} }
Buche, A.B. On an Exponential-Cosine Operator-Valued Functional Equation. (Short Communication).. Aequationes mathematicae, Tome 13 (1975) p. 117. http://gdmltest.u-ga.fr/item/GDZPPN002028573/