Adding a third stylesheet to my WP site

Hi,
somebody can help me adding a 3rd stylesheet to my site?
I’m a beginner in Php and tried to add a conditionnal tag to my header?php, expecting it to load a special css file if a special page is called.

The problem is that I can’t get it working. I assume I’m making
it in a wrong way, but I don’t know where is the mistake?

Here is my code:

<?php if ( is_page(array('About', 'Contact', 'Showreel')) ) { ?>
<link rel="stylesheet" href="<?php bloginfo('template_url'); ?>/styleLarge.css" type="text/css" media="screen" />
<?php elseif ( is_page('Blog') ):?>
<link rel="stylesheet" href="<?php bloginfo('template_url'); ?>/styleblog.css" type="text/css" media="screen" />
<?php } else { ?>
<link rel="stylesheet" href="<?php bloginfo('stylesheet_url'); ?>" type="text/css" media="screen" />
<?php } ?>

This is the blog page which is causing me problem. thanks