Rannite raždanija v Bălgarija prez vtorata polovina na XX vek - Čalăkova, Diana T. (Akad. Izdat. "Marin Drinov", 2004)
PST: Teenage births in Bulgaria during the second half of the 19th century. - In kyrill. Schr., bulg. - Zsfassung in engl. Sprache