1. Archives:
2. Secondary sources :
3. Archiv Ministerstva Zahraničních Věcí (Archive of the Ministry of Foreign Affairs Prague) (AMZV)
4. Archiwum Ministerstwa Spraw Zagranicznych (Archives of the Ministry of Foreign Affairs Warsaw) (AMSZ)
5. Arhivele Naţionale ale României (National Archives of Romania Bucharest) (ANR)