Error parsing XML document

http error : Unknown IO error
/prosjekt/wab/public_html/wab_agora.page:159: parser error : Entity 'auml' not defined
				    <xref url="http://www.uib.no/personer/Simo.Saatela">Simo S&auml;&auml;te
				                                                                    ^
/prosjekt/wab/public_html/wab_agora.page:159: parser error : Entity 'auml' not defined
				    <xref url="http://www.uib.no/personer/Simo.Saatela">Simo S&auml;&auml;te
				                                                                          ^
/prosjekt/wab/public_html/wab_agora.page:159: parser error : Entity 'auml' not defined
 <xref url="http://www.uib.no/personer/Simo.Saatela">Simo S&auml;&auml;tel&auml;
                                                                                ^
/prosjekt/wab/public_html/wab_agora.page:161: parser error : Entity 'oslash' not defined
<xref url="http://www.uib.no/personer/Sindre.Sorensen">Sindre S&oslash;rensen</x
                                                                       ^