He wrote numerous books about Yugoslav communist tactics in Europe, and crimes of the leadership of the Independent State of Croatia against the Serb population during World War II.
In 1936, he took his doctorate degree in the historical section of the faculty with a dissertation entitled "Stevan Stratimirović, Metropolitan of Sremski Karlovci as an Ecclesiastical, National, Political and Cultural Figure."
During the Second World War, he taught at the University of Belgrade, supported the Government of National Salvation under the command of general Milan Nedić,[2] and began collecting material on the Ustashi genocide of Serbs in the Independent State of Croatia.
[1] At the end of the war, he left Yugoslavia together with many freedom-fighters and intellectuals who were loyal to the ancien régime and opposed to Communism.
After fully mastering the German language in 1954, he moved from Bern, Switzerland to Munich, Germany where he joined the staff of the "Institute for Southeast European Studies"[4] as a reference officer for Albania and Bulgaria.