First Author:   George E. Halkos Department of Economics, University of Thessaly halkos@econ.uth.gr   University of Thessaly, Department of Economics, Korai 43 Volos, 38333, Greece   0030 24210 74920(Phone) 0030 24210 74920(Fax) http://www.halkos.gr/ Second Author: Nickolaos G. Tzeremes Department of Economics, University of Thessaly bus9nt@uth.gr   University of Thessaly, Department of Economics, Korai 43 Volos, 38333, Greece   0030 24210 74911(Phone)   http://ideas.repec.org/e/ptz6.html