l-shaped room speaker placement

This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I want to improve the speaker setup for a friend of mine who is just getting into hifi, but his room is far from optimal and I need your help. It's L-shaped and has two windows.
Dimensions of the part of the L, in which I can move the speakers arround are 2.5x3x4m (HxWxD) and the dimensions of the other L-part are 2.5x2.6x4.9 (HxWxD). The two widths come together to form the long part of the "L" if that makes sense. The two windows are both on that long wall -one sadly on the 3m part of the wall behind where the speakers are now.
UnfortunatelyI forgot to take some pictures of the room when I was there, but I made a quick sketch of the room in a homedesign software I used for my own house a few years ago -I marked all possible speaker positions with X's. Hopefully that's enough. I'm thinking about placing the speakers infront of the large bookshelf on the 4m wall.

Please help me. I would greatly appreciate it:)