How to sort [specific] multiple categories post in alphabetical order

Okay, I found this little bit of code;

############

<?php
// we add this, to show all posts in our
// Glossary sorted alphabetically
if (is_category(‘Glossary’))
{
$posts = query_posts($query_string .
‘&orderby=title&order=asc&posts_per_page=-1’);
}
// here comes The Loop!
if (have_posts()) : while (have_posts()) : the_post(); ?>

############

Which works an absolute treat! But does anyone know how I can apply this to [specific] multiple categories – not all the categories?