Multigrid methods proceedings of the conference held at Koln-Porz, November 23-27, 1981 / edited by W. Hackbusch and U. Trottenberg.

Multigrid methods II proceedings of the 2nd European Conference on Multigrid Methods, held at Cologne, October 1-4, 1985 / edited by W. Hackbusch and U. Trottenberg.