@incollection{Soft06,
author = "P. Meseguer and F. Rossi and T. Schiex",
booktitle = " Handbook of Constraint Programming ",
chapter = " 9 ",
editor = " Rossi, F. and van Beek, P. and Walsh, T. ",
publisher = " Elsevier ",
title = "{S}oft {C}onstraints {P}rocessing",
url = "http://www.elsevier.com/wps/find/bookdescription.cws_home/708863/description#description",
year = "2006",
}