Error parsing XML document

/mnt/stor/prosjekt/menota/public_html/katalog.page:12: parser error : Entity 'aring' not defined
            <title>R&aring;d for Menota</title>
                           ^
/mnt/stor/prosjekt/menota/public_html/katalog.page:69: parser error : Entity 'nbsp' not defined
<p>&nbsp;</p>
         ^
/mnt/stor/prosjekt/menota/public_html/katalog.page:80: parser error : Entity 'THORN' not defined
                     <item><title>&THORN;i&eth;reks saga af Bern</title>, Holm p
                                         ^
/mnt/stor/prosjekt/menota/public_html/katalog.page:80: parser error : Entity 'eth' not defined
                     <item><title>&THORN;i&eth;reks saga af Bern</title>, Holm p
                                               ^
/mnt/stor/prosjekt/menota/public_html/katalog.page:95: parser error : Entity 'Aacute' not defined
                  &Aacute;rna Magn&uacute;ssonar &aacute;
                          ^
/mnt/stor/prosjekt/menota/public_html/katalog.page:95: parser error : Entity 'uacute' not defined
                  &Aacute;rna Magn&uacute;ssonar &aacute;
                                          ^
/mnt/stor/prosjekt/menota/public_html/katalog.page:95: parser error : Entity 'aacute' not defined
                  &Aacute;rna Magn&uacute;ssonar &aacute;
                                                         ^
/mnt/stor/prosjekt/menota/public_html/katalog.page:96: parser error : Entity 'Iacute' not defined
                  &Iacute;slandi</head>
                          ^
/mnt/stor/prosjekt/menota/public_html/katalog.page:132: parser error : Entity 'nbsp' not defined
         <p>&nbsp;</p>  
                  ^
 at /usr/lib/perl5/site_perl/Aksis/XSLTransformer/Application.pm line 154