<ul>
<li><span style="font-weight: bold;">2009-12.</span> Helena
appears in F. Wiedijk's <a
- href="http://www.cs.ru.nl/%7Efreek/digimath/index.html">index of
+ href="http://www.cs.ru.nl/%7Efreek/digimath/index.html#helena">index of
computer math systems</a>.</li>
</ul>
</li>
<a style="font-style: italic;"
href="download/lambda_delta.txt">lambda_delta.txt</a> (revised <span
- style="font-weight: bold;">2010-07</span>).</li>
+ style="font-weight: bold;">2011-09</span>).</li>
</ul>
<ul>
<li>A <a href="http://www.jedsoft.org/jed/">Jed mode</a> for