How to save entities in as it is in xml file

Hi,

This is a XML file,In this file shows some entities ,I need that this entities to save as it is to another XML file

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE article PUBLIC "-//Atypon//DTD Atypon Systems Journal Archiving and Interchange NLM DTD v3.0.0 20090430//EN" "atypon-archivearticle3.dtd"><articlearticle-type="research-article"dtd-version="3.0"xml:lang="en"><issnpub-type="ppub">&#x0201C;15573060</issn><issnpub-type="epub">&#x0201C;15573079</issn><article-title>&#x0201C;Modern&#x0201D; Education Finance: How It Differs from the &#x0201C;Old&#x0201D; and It Implies</article-title><copyright-statement>&#x000A9; 2006 MIT Press</copyright-statement></article>

privatevoid button1_Click(object sender,EventArgs e){var doc=XDocument.Load(@"D:\a.xml");var writer =XmlWriter.Create(@"D:\a1.xml",newXmlWriterSettings{Encoding=Encoding.UTF8});

            doc.Save(writer);}