Sovetsko-bolgarskie otnoshenii︠a︡ i svi︠a︡zi : dokumenty i materialy /
Valev, L. B.
Khristov, Khristo Angelov.
Institut slavi︠a︡novedenii︠a︡ i balkanistiki (Akademii︠a︡ nauk SSSR)1n
Institut za istorii︠a︡ (Bŭlgarska akademii︠a︡ na naukite)
Moskva : "Nauka,"
1976-
Includes bibliographical references and index.