TY - JOUR AU - H. Calandra AU - S. Gratton AU - R. Lago AU - X. Pinel AU - X. Vasseur TI - Two-level preconditioned Krylov subspace methods for the solution of three-dimensional heterogeneous Helmholtz problems in seismics JO - Sibirskij žurnal vyčislitelʹnoj matematiki PY - 2012 SP - 213 EP - 221 VL - 15 IS - 2 PB - mathdoc UR - http://geodesic.mathdoc.fr/item/SJVM_2012_15_2_a11/ LA - ru ID - SJVM_2012_15_2_a11 ER -