@phdthesis{Friese1999,
author = {Friese, Tilman},
year = {1999},
title = {Eine Mehrgitter-Methode zur Lösung des Eigenwertproblems der komplexen
Helmholtzgleichung},
type = {Dissertation},
url = "http://dx.doi.org/10.17169/refubium-12868",
}