Posting on FB

Hi

I'm looking for FB groups poster software to market my books on FB. I actually find it very helpful on free promo days for getting downloads and reviews. There are a few softwares out there. I don't know which one to choose...

Do you know anything about it?

Here are a few softwares:
http://www.seanwalters.com/facebook-groups-poster-software/?id=nelmart718
http://www.toolsstar.com/index.php?affiliate=6393
http://www.sharecron.com/facebook-sharer-demo.php