collapse_list.html

<ul class="events">
  <li><span class="collapsible open">2010</span>
    <ul>
      <li><span class="collapsible closed">January</span>
        <ul>
          <li>
            <p class="collapsible closed">Primary Content Identifier 1</p>
            <p>Primary Content</p>
          </li>

          <li>
            <p class="collapsible closed">Primary Content Identifier 2</p>
            <p>Primary Content</p>
          </li>

          <li>
            <p class="collapsible closed">Primary Content Identifier 3</p>
            <p>Primary Content</p>
          </li>
        </ul>
      </li>
    </ul>
  </li>
</ul>