Uchebnik no Bŭlgarski ezik za chuzhdentsi = A Bulgarian textbook for foreigners /
Ginina, Stefaniia T︠S︡vetanova.
Nikolova, Tsvetana Nikiforova.
Sakzova, Li︠u︡ba Anastasova.
Sofii︠a︡ :  Nayka i izkustvo, 
1972.
Bulgarian language