The d-dimensional Helmholtz equationon sparse grids - Robert Balder; Christoph Zenger 001 (Forschungsberichte, TU Munich, 1992)

The Solution of Multidimensional Real Helmholtz Equations on Sparse Grids. - Robert Balder; Christoph Zenger 001 (SIAM J. Sci. Comput., 1996)