diff --git a/doc/src/sgml/pgcrypto.sgml b/doc/src/sgml/pgcrypto.sgml
index d8ba9f26b11..b75e0de14ba 100644
--- a/doc/src/sgml/pgcrypto.sgml
+++ b/doc/src/sgml/pgcrypto.sgml
@@ -1287,72 +1287,6 @@ gen_random_uuid() returns uuid
     ciphertexts of a given size.
    </para>
   </sect3>
-
-  <sect3>
-   <title>Useful Reading</title>
-
-   <itemizedlist>
-    <listitem>
-     <para><ulink url="https://www.gnupg.org/gph/en/manual.html"></ulink></para>
-     <para>The GNU Privacy Handbook.</para>
-    </listitem>
-    <listitem>
-     <para><ulink url="https://www.openwall.com/crypt/"></ulink></para>
-     <para>Describes the crypt-blowfish algorithm.</para>
-    </listitem>
-    <listitem>
-     <para>
-      <ulink url="https://www.iusmentis.com/security/passphrasefaq/"></ulink>
-     </para>
-     <para>How to choose a good password.</para>
-    </listitem>
-    <listitem>
-     <para><ulink url="http://world.std.com/~reinhold/diceware.html"></ulink></para>
-     <para>Interesting idea for picking passwords.</para>
-    </listitem>
-    <listitem>
-     <para>
-      <ulink url="http://www.interhack.net/people/cmcurtin/snake-oil-faq.html"></ulink>
-     </para>
-     <para>Describes good and bad cryptography.</para>
-    </listitem>
-   </itemizedlist>
-  </sect3>
-
-  <sect3>
-   <title>Technical References</title>
-
-   <itemizedlist>
-    <listitem>
-     <para><ulink url="https://tools.ietf.org/html/rfc4880"></ulink></para>
-     <para>OpenPGP message format.</para>
-    </listitem>
-    <listitem>
-     <para><ulink url="https://tools.ietf.org/html/rfc1321"></ulink></para>
-     <para>The MD5 Message-Digest Algorithm.</para>
-    </listitem>
-    <listitem>
-     <para><ulink url="https://tools.ietf.org/html/rfc2104"></ulink></para>
-     <para>HMAC: Keyed-Hashing for Message Authentication.</para>
-    </listitem>
-    <listitem>
-     <para>
-      <ulink url="https://www.usenix.org/legacy/events/usenix99/provos.html"></ulink>
-     </para>
-     <para>Comparison of crypt-des, crypt-md5 and bcrypt algorithms.</para>
-    </listitem>
-    <listitem>
-     <para>
-      <ulink url="https://en.wikipedia.org/wiki/Fortuna_(PRNG)"></ulink>
-     </para>
-     <para>Description of Fortuna CSPRNG.</para>
-    </listitem>
-    <listitem>
-     <para><ulink url="https://jlcooke.ca/random/"></ulink></para>
-     <para>Jean-Luc Cooke Fortuna-based <filename>/dev/random</filename> driver for Linux.</para>
-    </listitem>
-   </itemizedlist>
-  </sect3>
  </sect2>
 
  <sect2>