Istoriia Bolgarii do 9 sentiabria 1944

D. D. Ivanov, Fundamentalʹnai︠a︡ biblioteka obshchestvennykh nauk (Akademii︠a︡ nauk SSSR), La.). Forest Inventory and Analysis Research Work Unit. Bŭlgarski bibliografski institut Southern Forest Experiment Station (New Orleans, N. V. Busse, Todor Bozov, Shunkov, V. I.