diff --git a/source/installation-guide/debian-8.rst b/source/installation-guide/debian-8.rst
index dafde777..9e5031ac 100644
--- a/source/installation-guide/debian-8.rst
+++ b/source/installation-guide/debian-8.rst
@@ -1,50 +1,50 @@
 .. _installation-guide-debian-8:
 
 ====================================
 Installation of Kolab 16 on Debian 8
 ====================================
 
 .. WARNING::
 
     This document sets you up with the version of Kolab that is maintained by
     the community. Customers of `Kolab Systems AG`_ join us
-    :ref:`here <https://kb.kolabenterprise.com/documentation/installation-of-kolab-16/installation-instructions-for-kolab-16-on-debian-8>`.
+    `here <https://kb.kolabenterprise.com/documentation/installation-of-kolab-16/installation-instructions-for-kolab-16-on-debian-8>`_.
 
 1.  Add the following two lines to ``/etc/apt/sources.list.d/kolab.list``:
 
     .. parsed-literal::
 
         deb http://obs.kolabsys.com/repositories/Kolab:/16/Debian_8.0/ ./
         deb-src http://obs.kolabsys.com/repositories/Kolab:/16/Debian_8.0/ ./
 
 2.  Import the GPG key used to sign the packages:
 
     .. parsed-literal::
 
         # :command:`wget -q -O- https://ssl.kolabsys.com/community.asc | apt-key add -`
 
 3.  To ensure the Kolab packages have priority over the Debian packages, such as
     must be the case for PHP as well as Cyrus IMAP, please make sure the APT
     preferences pin the obs.kolabsys.com origin as a preferred source.
 
     Put the following in ``/etc/apt/preferences.d/kolab``:
 
     .. parsed-literal::
 
         Package: *
         Pin: origin obs.kolabsys.com
         Pin-Priority: 501
 
 4.  Update the repository metadata:
 
     .. parsed-literal::
 
         # :command:`apt-get update`
 
 5. Start the installation of the base package as follows:
 
     .. parsed-literal::
 
         # :command:`aptitude -y install kolab`
 
 Continue to :ref:`installation-guide-setup-kolab`.
diff --git a/source/installation-guide/debian-9.rst b/source/installation-guide/debian-9.rst
index 0f6e8bcb..1476b4d5 100644
--- a/source/installation-guide/debian-9.rst
+++ b/source/installation-guide/debian-9.rst
@@ -1,50 +1,50 @@
 .. _installation-guide-debian-9:
 
 ====================================
 Installation of Kolab 16 on Debian 9
 ====================================
 
 .. WARNING::
 
     This document sets you up with the version of Kolab that is maintained by
     the community. Customers of `Kolab Systems AG`_ join us
-    :ref:`here <https://kb.kolabenterprise.com/documentation/installation-of-kolab-16/installation-instructions-for-kolab-16-on-debian-9>`.
+    `here <https://kb.kolabenterprise.com/documentation/installation-of-kolab-16/installation-instructions-for-kolab-16-on-debian-9>`_.
 
 1.  Add the following two lines to ``/etc/apt/sources.list.d/kolab.list``:
 
     .. parsed-literal::
 
         deb http://obs.kolabsys.com/repositories/Kolab:/16/Debian_9.0/ ./
         deb-src http://obs.kolabsys.com/repositories/Kolab:/16/Debian_9.0/ ./
 
 2.  Import the GPG key used to sign the packages:
 
     .. parsed-literal::
 
         # :command:`wget -q -O- https://ssl.kolabsys.com/community.asc | apt-key add -`
 
 3.  To ensure the Kolab packages have priority over the Debian packages, such as
     must be the case for PHP as well as Cyrus IMAP, please make sure the APT
     preferences pin the obs.kolabsys.com origin as a preferred source.
 
     Put the following in ``/etc/apt/preferences.d/kolab``:
 
     .. parsed-literal::
 
         Package: *
         Pin: origin obs.kolabsys.com
         Pin-Priority: 501
 
 4.  Update the repository metadata:
 
     .. parsed-literal::
 
         # :command:`apt-get update`
 
 5. Start the installation of the base package as follows:
 
     .. parsed-literal::
 
         # :command:`aptitude -y install kolab`
 
 Continue to :ref:`installation-guide-setup-kolab`.
diff --git a/source/installation-guide/ubuntu-16.04.rst b/source/installation-guide/ubuntu-16.04.rst
index a92a4eeb..52120a7b 100644
--- a/source/installation-guide/ubuntu-16.04.rst
+++ b/source/installation-guide/ubuntu-16.04.rst
@@ -1,50 +1,50 @@
 .. _installation-guide-ubuntu-16.04:
 
 ========================================
 Installation of Kolab 16 on Ubuntu 16.04
 ========================================
 
 .. WARNING::
 
     This document sets you up with the version of Kolab that is maintained by
     the community. Customers of `Kolab Systems AG`_ join us
-    :ref:`here <https://kb.kolabenterprise.com/documentation/installation-of-kolab-16/installation-instructions-for-kolab-16-on-ubuntu-16-04>`.
+    `here <https://kb.kolabenterprise.com/documentation/installation-of-kolab-16/installation-instructions-for-kolab-16-on-ubuntu-16-04>`_.
 
 1.  Add the following two lines to ``/etc/apt/sources.list.d/kolab.list``:
 
     .. parsed-literal::
 
         deb http://obs.kolabsys.com/repositories/Kolab:/16/Ubuntu_16.04/ ./
         deb-src http://obs.kolabsys.com/repositories/Kolab:/16/Ubuntu_16.04/ ./
 
 2.  Import the GPG key used to sign the packages:
 
     .. parsed-literal::
 
         # :command:`wget -q -O- https://ssl.kolabsys.com/community.asc | apt-key add -`
 
 3.  To ensure the Kolab packages have priority over the Ubuntu packages, such
     as must be the case for PHP as well as Cyrus IMAP, please make sure the APT
     preferences pin the obs.kolabsys.com origin as a preferred source.
 
     Put the following in ``/etc/apt/preferences.d/kolab``:
 
     .. parsed-literal::
 
         Package: *
         Pin: origin obs.kolabsys.com
         Pin-Priority: 501
 
 4.  Update the repository metadata:
 
     .. parsed-literal::
 
         # :command:`apt-get update`
 
 5. Start the installation of the base package as follows:
 
     .. parsed-literal::
 
         # :command:`aptitude -y install kolab`
 
 Continue to :ref:`installation-guide-setup-kolab`.