facebook, google, twitter, linked in login buttons

I'm trying to setup single sign on (SSO) logins for each of these services. I have already setup facebook with a simple 开发者_开发百科piece of code they provide like so:

<fb:login-button>Facebook</fb:login-button>
<div id="fb-root"></div>
<script src="http://connect.facebook.net/en_US/all.js"></script>
<script>
    FB.init({appId: '<?php echo $facebook_app_id; ?>', status: true, cookie: true, xfbml: true});
    FB.Event.subscribe('auth.login', function(response) { window.location.reload(); });
</script>

This creates a button for you and when you click on it opens up pop up window where you can login and allow the app website access to your facebook account. Is there anything simple like this for google, twitter and linkedin?

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For LinkedIn: https://developer.linkedin.com/documents/sign-linkedin