Japan Center for Asia Historical Materials (JACAR), Minzoku mondai kankei zakken: Yudayajin mondai [Documents on the Issus of Nationalities: The Jewish Issue] B04013207600-10500, 11:391-392. Original in Japanese.
National Archives and Records Administration II, RG 59 - Records of the Department of State relating to internal affairs of Bulgaria 1910-1944, Washington 1982 (Mikrofilm-Edition): Doc. 874.4016/68, p. 1f. Original in English.