This is a Perl site, not man sort.
To bring things on topic, investigate the sorting in Perl with the sort perldoc and japhy's excellent Resorting to Sorting.
You might also find the following nodes useful:
If that doesn't help, try File::Sort or the Perl Power Tools version of sort. Either way, you'll probably need to read the manpage for sort and try it for yourself. I had the same problem figuring sort key definitions the other day - it took a few minutes tinkering before I understood it - you should try too.
If the information in this post is inaccurate, or just plain wrong, don't just downvote - please post explaining what's wrong.
That way everyone learns.