How the heck can they be "Jew" free? On the first flat/floor of my friends apartment, there is a Serbian-Jewish Friendship Committee office that has been there for well, well over twenty years.
Serbia was the first to rise up against the Germans in all of Europe. They were the quickest to form anti-Axis forces and were the most effective til Tito usurped the intel in London to have support switched from the Serbs to his communist heathens.
First Junenfrei town in the balkans (and Europe) was Sarajevo, not Belgrade.
Sarajevo at that time was in Nazi puppet statelet called Independent State of Croatia, run by Croatian Nazis.
Unlike Bosnia and Croatia (a.k.a Independent State of Croatia), WWII Serbia was under direct Wehrmacht military occupation. An attempt to blame extermination of Jews on Serbs is an act of Holocaust revisionism, because it tries to exonerate Nazism and Nazis, the real perpetrators of extermination and pin it on Serbs as a people.
It will be better for your mental health to read Holocaust encyclopaedia than Croatian Nazi drivel. Denial is not a river in Egypt.