Singing from Yol (film)

[Zert]

Hello all,

I registered on this forum because some music from Yol (the film by Yilmaz Guney) was in my head. I really like the singing, but I never found the artist or what the piece of music is called, it's not on the official soundtrack of the film either.

So, I'd be very happy if you all could help me with finding who is singing/what the name of the song is/the lyrics of the song.
There seems to be multiple versions of it:

http://video.google.com/videoplay?docid=-3194792110120066551#
Starts around 25:30 in this one.
Also a shorter piece is in 3:00 in the same video.

http://www.youtube.com/watch?v=Lhcd8DIsfyM
Here's the altered version of the film.
You can hear the fragment at around 4:00 here.

http://www.youtube.com/watch?v=oniV5MU2rOE&feature=related
And around 5:50 in this one.

Also small bits of it can be heard in other parts of the film.

So can someone please help me with this?
Thanks in advance.