diff --git a/LDP/guide/docbook/solrhe/Securing-Optimizing-Linux-RH-Edition-v1.3.xml b/LDP/guide/docbook/solrhe/Securing-Optimizing-Linux-RH-Edition-v1.3.xml
index c711cc41..0cd9b2b2 100644
--- a/LDP/guide/docbook/solrhe/Securing-Optimizing-Linux-RH-Edition-v1.3.xml
+++ b/LDP/guide/docbook/solrhe/Securing-Optimizing-Linux-RH-Edition-v1.3.xml
@@ -1,5 +1,5 @@
 <?xml version='1.0' encoding="iso-8859-1" standalone='no'?>
-<!DOCTYPE article PUBLIC '-//OASIS//DTD DocBook XML V4.1.2//EN' 
+<!DOCTYPE book PUBLIC '-//OASIS//DTD DocBook XML V4.1.2//EN' 
   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" []>
 
 <book><!-- <?dbhtml filename="coverpage.html"?> -->