All over the place, google Experts Kosovo Genocide.
While you're at it you might take a look at a real tradgedy:
You do understand the difference between a proof and a counter-claim, yes?
There are always dissenting opinions about historical events. There are still those who claim the Holocaust never happened, for instance. So it doesn't surprise me that there is a school of thought which wants to cast doubt on the occurrence of a massacre at Srebrenica. But proof? That's another level.
Your Kosovo reference escapes me. The men quoted in the article were quizzed about Srebrenica, no?