Sorry, quick question: I keep seeing it spelled Slibah and Sliabh. Which one is correct?

Also, I'm off tonight--right now--but will be working tonight and tomorrow night. I sleep during the day, so do not be alarmed if I am slightly late to the party! But I have Thurs, Fri, and Sat off. (8 If I can't get a post in today or tomorrow, expect one on Thursday. Sorry for any troubles this causes. I'll be thinking about my first post in the mean time. *thumbs up*