@phdthesis{Koster99b,
author = "A M C A. Koster",
address = "The Netherlands",
month = "nov",
note = "Available at www.zib.de/koster/thesis.html.",
school = "University of Maastricht",
title = "{F}requency assignment: {M}odels and {A}lgorithms",
year = "1999",
}