Density-Matrix Renormalization - A New Numerical Method in Physics : Lectures of a Seminar and Workshop held at the Max-Planck-Institut für Physik komplexer Systeme, Dresden, Germany, August 24th to September 18th, 1998 - Ingo Peschel, Matthias Kaulke, Xiaoqun Wang, Karen Hallberg ((Lecture Notes in Physics))