用第二个参数改变Mod Rewrite

I am currently working on an URL shortener for my blog, as the URLs have become very long over the years. Everything works well so far, only I do not get the second variable on the "redirect.php" resolved.

This should be from the following URL. http://example.com/bM/bla1.html --> content.php?alias=bM&ref=bla1

So far the call works on http://example.com/bM It will resolve correctly to the content.php?alias=bM

Unfortunately, I do not get the second variable resolved. I've already tried different instructions but unfortunately i don't understand RegExp very good.

<IfModule mod_rewrite.c>
    RewriteEngine on
    RewriteOptions MaxRedirects=1
    RewriteBase /
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteCond %{REQUEST_FILENAME} !-l
    RewriteRule ^([a-zA-Z0-9_-]+)$ content.php?alias=$1 [L]
    RewriteCond %{SERVER_PORT} !^443$
</IfModule>