The right has no monopoly on the truth. The left does not have, and never has, anything to do with the truth as a matter of principle.
I recommend you a book by a US Socialist Michael Parenti:
Parenti, by virtue of the fact that he is an admitted Marxist, cannot be trusted.
He is also the lunatic who claims that the US intentionally and specifically bombed civilian targets in Belgrade in order to destroy Communist banners and murals.
Parenti is a screaming, raving moonbat and I regret the time I've lost reading a couple of his articles on this topic.
I have no desire to read anything else by him. Life is too short.
His facts and arguments in this book - To Kill A Nation stand on their own. And they do not depend on his world-view. You should read it.
Also you should not trust or distrust someone statement on the base of which political affiliation someone has. Even the members of very correct political movements happen to be wrong and people of incorrect views happen to be rights.
In matters of Yugoslavia Parenti is often right. And if he is a Socialist it sheds a good light on Socialism.