Austrian Agency for International Cooperation in Education and Research (OeAD )Austrian Agency for International Cooperation in Education and Research (OeAD )

Bulgarian National Science Fund (BNSF)

Austrian State Archive /Archive of the Republic (ÖStA/AdR), Helmut Wohnout

Central State Archive of the Republic of Bulgaria /Centralen dărzhaven arhiv na Republika Bulgaria (CDA) 

Archive of the Ministry of Foreign Affairs of the Republic of Bulgaria / Arhiv na Ministerstvo na vănshnite raboti na Republika Bălgaria (AMVnR) 

Stiftung Bruno Kreisky Archive (SBKA)

Mark Kramer, Harvard University