Aleksandrov, Valentin: Brest-Litovskii︠a︡t miren dogovor 1918 g. Voennostrategicheski prichini i mezhdunarodnopravni posledit︠s︡i (The Brest-Litovsk Peace Treaty 1918. Military-strategic reasons and international legal consequences), Sofia, 2009: Voenno izdatelstvo.