Pierluigi Amodio Ivonne Sgura High Order Finite Difference Schemes for the Solution of Elliptic PDEs. 1-6 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3314&spage=1 2004 conf/cis/2004 CIS db/conf/cis/cis2004.html#AmodioS04