Atmos Speaker placement


I have an extra pair of some nice DIY book shelve speakers that I would like to use as an overhead Atmos speaker.
Where is the best placement? Up high tilting down? In the middle of the room? etc.

Thanks,
ozzy
128x128ozzy
Post removed 
Thanks.
It looks like the sound can be bounced off the ceiling. 
I was thinking that with my side speakers on stands I could have them pointing towards the ceiling. Or perhaps angled a bit.
Would that suffice?

ozzy
Follow the guidelines in the dolby link, it worked nicely for me, if anything i would go slightly wider than explained by dolby....