<div class="panel-group" id="accordion">
  <div class="panel panel-default">
    <div class="panel-heading">
      <h4 class="panel-title">
        <a class="accordion-toggle" data-toggle="collapse" href="#collapSEOne">
          Collapsible Group Item #1
        </a>
      </h4>
    </div>
     ...

http://bootply.com/127843