Hakopian, Y. H.; Hovhannisyan, H. A. ALGEBRAIC MULTIGRID PRECONDITIONER FOR SECOND ORDER FINITE ELEMENT APPROXIMATIONS IN RECTANGULAR DOMAINS. II. MULTIGRID PRECONDITIONER. Proc. YSU A: Phys. Math. Sci. 2003, 37 (2 (201), 18-24. https://doi.org/10.46991/PYSUA.2003.37.2.018.