diff --git a/LDP/guide/docbook/Linux-Dictionary/Linux-Dictionary.xml b/LDP/guide/docbook/Linux-Dictionary/Linux-Dictionary.xml
index 62dad200..629033dc 100644
--- a/LDP/guide/docbook/Linux-Dictionary/Linux-Dictionary.xml
+++ b/LDP/guide/docbook/Linux-Dictionary/Linux-Dictionary.xml
@@ -1,6 +1,6 @@
 <?xml version='1.0' encoding='UTF-8'?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
-"http://www.oasis-open.org/docbook/xml/4.0/docbookx.dtd"[
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"[
 <!ENTITY About-the-Author SYSTEM "About-the-Author.xml">
 <!ENTITY Contributors SYSTEM "Contributors.xml">
 <!ENTITY Disclaimer   SYSTEM "Disclaimer.xml">