Ali Sayfy Sadia M. Makky Numerical Solution of Inverse Problem for Elliptic PDEs. 665-670 2003 80 Int. J. Comput. Math. 5 http://taylorandfrancis.metapress.com/openurl.asp?genre=article&issn=0020-7160&volume=80&issue=5&spage=665 db/journals/ijcm/ijcm80.html#SayfyM03