showdownjs/test/cases/anchors-by-reference.html

<p>This is <a href="http://example.com/" title="Optional Title Here">an example</a> reference-style link.
  This is <a href="http://example.com/" title="Optional Title Here">another</a> reference-style link.
  This is <a href="http://example.com/" title="Optional Title Here">a third</a> reference-style link.
  This is <a href="http://example.com/" title="Optional Title Here">a fourth</a> reference-style link.</p>