diff --git a/LDP/guide/docbook/Intro-Linux/abook.xml b/LDP/guide/docbook/Intro-Linux/abook.xml
index 08a64e94..2a203da2 100644
--- a/LDP/guide/docbook/Intro-Linux/abook.xml
+++ b/LDP/guide/docbook/Intro-Linux/abook.xml
@@ -656,6 +656,7 @@
                     <para>
                         <xref linkend="app4"/>: What you can do with this guide, from the legal perspective.</para>
                 </listitem>
+		<listitem><para><xref linkend="app5"/>: documentation about the <filename>/proc</filename> file system.</para></listitem>
             </itemizedlist>
 
 <informalfigure>