An algebraic multigrid based shifted-Laplacian preconditioner for the Helmholtz equation. - Tuomas Airaksinen; Erkki Heikkola; Anssi Pennanen; Jari Toivanen (J. Comput. Phys., 2007)

A damping preconditioner for time-harmonic wave equations in fluid and elastic material. - Tuomas Airaksinen; Anssi Pennanen; Jari Toivanen (J. Comput. Phys., 2009)

Comparison between the shifted-Laplacian preconditioning and the controllability methods for computational acoustics. - Tuomas Airaksinen; Sanna Mönkölä (J. Comput. Appl. Math., 2010)