diff --git a/Doc/Common/glossary.xml b/Doc/Common/glossary.xml
index 87e97747808e951cdd8363e0210acdcff31c5a5e..176683af9e60ac9278d73120a543a037d03e88a2 100644
--- a/Doc/Common/glossary.xml
+++ b/Doc/Common/glossary.xml
@@ -103,6 +103,16 @@
       </glossdef>
     </glossentry>
 
+    <glossentry xml:id="glo_EPUB">
+      <glossterm><acronym>Epub</acronym></glossterm>
+
+      <glossdef>
+        <para>An ISO <link
+        xlink:href="https://en.wikipedia.org/wiki/EPUB">Electronic
+        Publication</link> standard.</para>
+      </glossdef>
+    </glossentry>
+
     <glossentry xml:id="glo_Ftp">
       <glossterm><acronym>Ftp</acronym></glossterm>
 
@@ -430,6 +440,17 @@
       </glossdef>
     </glossentry>
 
+    <glossentry xml:id="glo_PDF">
+      <glossterm><acronym>PDF</acronym></glossterm>
+
+      <glossdef>
+        <para><orgname xlink:href="https://www.adobe.com">Adobe's</orgname>
+        <link
+        xlink:href="https://en.wikipedia.org/wiki/Portable_Document_Format">Portable
+        Document Format</link> standard.</para>
+      </glossdef>
+    </glossentry>
+
     <glossentry xml:id="glo_PHP">
       <glossterm><acronym>PHP</acronym></glossterm>
 
diff --git a/Doc/lectures.xml b/Doc/lectures.xml
index 73c54b19da3b78fc9c866095cecbb4a5c4efd8bb..e06e3558876c68a456b836b023c922fb0b6d617c 100644
--- a/Doc/lectures.xml
+++ b/Doc/lectures.xml
@@ -25,14 +25,9 @@
     </legalnotice>
 
     <abstract>
-      <para>This Document is available in <link linkend="ava">multiple
-      formats</link>.</para>
-
-      <para><mediaobject>
-          <imageobject>
-            <imagedata fileref="Sd1/Ref/Svg/freedocs.svg" scale="50"/>
-          </imageobject>
-        </mediaobject></para>
+      <para>This Document is available in <link
+      linkend="availableFormats"><xref linkend="glo_PDF"/>, <xref
+      linkend="glo_EPUB"/> and other formats</link>.</para>
     </abstract>
   </info>
 
diff --git a/Doc/preface.xml b/Doc/preface.xml
index 367026ec80ae1d535600327c37958ee2e04bdeac..ae54dcc8b560d82403c45383d0e98de6f8853321 100644
--- a/Doc/preface.xml
+++ b/Doc/preface.xml
@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <preface version="5.0" xml:id="preface" xmlns="http://docbook.org/ns/docbook"
          xmlns:xlink="http://www.w3.org/1999/xlink"
+         xmlns:xila="http://www.w3.org/2001/XInclude/local-attributes"
          xmlns:xi="http://www.w3.org/2001/XInclude"
          xmlns:svg="http://www.w3.org/2000/svg"
          xmlns:m="http://www.w3.org/1998/Math/MathML"
@@ -37,11 +38,10 @@
       xlink:href="https://freedocs.mi.hdm-stuttgart.de/webhelp/lectures.epub">lectures.epub</filename></glossterm>
 
       <glossdef>
-        <para><productname
-        xlink:href="https://en.wikipedia.org/wiki/EPUB">Epub</productname>
-        containing <xref linkend="glo_SVG"/> images and MathML formulas based
-        on <link xlink:href="https://www.mathjax.org">MathJax
-        JavaScript</link> rendering.</para>
+        <para> <xref linkend="glo_EPUB"/> containing <xref linkend="glo_SVG"/>
+        images and MathML formulas based on <link
+        xlink:href="https://www.mathjax.org">MathJax JavaScript</link>
+        rendering.</para>
 
         <caution>
           <para>Some older <productname
@@ -58,10 +58,8 @@
       xlink:href="https://freedocs.mi.hdm-stuttgart.de/webhelp/printversion.pdf">printversion.pdf</filename></glossterm>
 
       <glossdef>
-        <para><productname
-        xlink:href="https://en.wikipedia.org/wiki/Portable_Document_Format">PDF</productname>
-        document providing sophisticated printout typography
-        (hopefully!).</para>
+        <para> <xref linkend="glo_PDF"/> document providing sophisticated
+        printout typography (hopefully!).</para>
 
         <caution>
           <para>These lecture notes are heavily based both on external links
@@ -73,15 +71,12 @@
     </glossentry>
 
     <glossentry>
-      <glossterm><productname
-      xlink:href="http://docbook.sourceforge.net/release/xsl/current/webhelp/docs">Web
-      help</productname> zip archive</glossterm>
+      <glossterm><link
+      xlink:href="https://freedocs.mi.hdm-stuttgart.de/webhelp/lectures.zip">lectures.zip</link></glossterm>
 
       <glossdef>
-        <para>Self contained <link
-        xlink:href="https://freedocs.mi.hdm-stuttgart.de/webhelp/lectures.zip">zip
-        archive</link> of previously mentioned resources for offline usage.
-        Does contain the following offline links:</para>
+        <para>Self contained zip archive of previously mentioned resources for
+        offline usage. Does contain the following offline links:</para>
 
         <itemizedlist>
           <listitem>
@@ -97,4 +92,10 @@
       </glossdef>
     </glossentry>
   </glosslist>
+
+  <mediaobject>
+    <imageobject>
+      <imagedata fileref="Sd1/Ref/Svg/freedocs.svg" scale="50"/>
+    </imageobject>
+  </mediaobject>
 </preface>