Luca Forlizzi Juraj Hromkovic Guido Proietti Sebastian Seibert On the Stability of Approximation for Hamiltonian Path Problems. 147-156 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3381&spage=147 2005 conf/sofsem/2005 SOFSEM db/conf/sofsem/sofsem2005.html#ForlizziHPS05