1. An improved two‐grid preconditioner for the solution of three‐dimensional Helmholtz problems in heterogeneous media‡. Issue 4 (22nd October 2012) Authors: Calandra, Henri; Gratton, Serge; Pinel, Xavier; Vasseur, Xavier Other Names: Borzi Alfio guestEditor.; Oosterlee Cornelis guestEditor. Journal: Numerical linear algebra with applications Issue: Volume 20:Issue 4(2013:Jul.) Page Start: 663 Record Type: Journal Article View Content: Available online (eLD content is only available in our Reading Rooms) ↗