“…This paper is concerned with the inverse source problem of determining f from the boundary measurements upx, kq, ∇upx, kq, ∆upx, kq, ∇∆upx, kq, x P BB R corresponding to the wavenumber k given in a finite interval. In general, there is no uniqueness for the inverse source problems of the wave equations at a fixed frequency [2,12]. Computationally, a more serious issue is the lack of stability, i.e., a small variation of the data might lead to a huge error in the reconstruction.…”