<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="//apps.bdimg.com/libs/bootstrap/3.3.0/css/bootstrap.min.css">
<p>Asterisk icon: <span class="glyphicon glyphicon-asterisk"></span></p>
<p>Asterisk icon as a link:
<span class="glyphicon glyphicon-asterisk"></span>
<p>Asterisk icon on a button:
<button type="button" class="btn btn-default btn-sm">
<span class="glyphicon glyphicon-asterisk"></span> Asterisk
<p>Asterisk icon on a styled link button:
<a href="#" class="btn btn-info btn-lg">
<span class="glyphicon glyphicon-asterisk"></span> Asterisk
<script src="//apps.bdimg.com/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="//apps.bdimg.com/libs/bootstrap/3.3.0/js/bootstrap.min.js"></script>