PageHeader : Funkcialaj Ekvacioj, 32 (1989) 479-481 Title : On a Functional Equation over Hilbert Spaces AuthorInfo : By AuthorInfo : A. B. Thaheem* and Noor Mohammad AuthorInfo : (International Centre for Theoretical Physics, Italy) section : 1. Introduction section : 2. Decomposition of a Hilbert space section : Acknowledgements section : References