Sources used for the 4 Parts the details are inside the articles just by name:
Sima Cirkovic, John V.A. Fine, Stevan K. Pavlowitch, Encyclopaedia Britannica, New World Encyclopedia, Saint Sava, Stefan Dusan, Thomas A. Emmert, Wayne S. Vucinich, John Matthias, Vladeta Vuckovic, Vuk Stefanovic Karadzic, Decani chrysobulls, Dusan Batakovic, UNESCO, Google Arts and Culture, Tim Judah, Albert Lord, Jacob Grimm, Leopold von Ranke, Michael Boro Petrovich, Sretenje Constitution, Paris Peace Conference, Frank Notestein, Radivojevic and Penev, Slobodan G. Markovich, Serbian Academy of Sciences and Arts, Royal Family of Serbia archives, Muzej Jugoslavije, Universal Newsreel 1934, Public Domain Review, Wikimedia Commons, United States Holocaust Memorial Museum, Gustav Gavrin, Kosta Hlavaty, Jasenovac Memorial Site, Jozo Tomasevich, Bogoljub Kocovic, Vladimir Zerjavic, Edmund Glaise von Horstenau, Bogdan Bogdanovic, SANU Memorandum, Vecernje Novosti, ICTY, United Nations, Croatian Helsinki Committee, MPRI, Associated Press, BBC, Ranko Cukovic, Human Rights Watch, Canadian Department of National Defence, 2 PPCLI, Canadian War Museum, Evan Kohlmann, Jo Angerer, Mathias Werth, WDR / ARD, Frankfurter Rundschau, Helena Ranta, Kaius Niemi, Helsingin Sanomat, WSWS, Forensic Science International, Le Figaro, Le Monde, Berliner Zeitung, The Sunday Times of London, FAIR, Heinz Loquai, Institute for War and Peace Reporting, Amnesty International, RFE/RL, Balkan Insight, Heinrich Boll Stiftung, Getty Images, Serbian Orthodox Church, OSCE, UNMIK, Jutarnji List, Euronews, Lossi36, Serbian Government, European Commission, Serbian Ministry of Foreign Affairs, Belgrade Centre for Security Policy, Serbian Ministry of Diaspora, Statistical Office of the Republic of Serbia, Karolina Novinscak, Vladimir Ivanovic, Vladimir Orel, Bardhyl Demiraj, Eric Hamp, Eqrem Cabej, Ion I. Russu, Vladimir Georgiev, Ivan Duridanov, Panagiotis G. Krimpas, Hans Krahe, Anton Mayer, Inigo Olalde, Pablo Carrion, Carles Lalueza-Fox, David Reich, Miodrag Grbic, Cell, bioRxiv, Ikerbasque Foundation, EurekAlert, PhysOrg, Western University News, El-lipse PRBB, Kacar et al., Srejic et al., Pavlovic et al., Noel Malcolm, J.G. von Hahn, Robert Elsie, Stephanie Schwandner-Sievers, Bernd J. Fischer, Chilcot Report, Hans Blix, Seymour Hersh, OPCW, WikiLeaks, Theodore Postol, Richard Lloyd, Ian Henderson, Patrick Cockburn, Stephen Cohen, Richard Sakwa, John Mearsheimer, Foreign Policy, TASS, European Consortium for Political Research, Maryland Journal of International Law