The Thermal Bath in Sliven Mineral Baths In: D. N. Kochankov. Sliven Mineral Baths, Sofia: Медицина и физкултура, 1962, p. 9
The Thermal Bath in Sliven Mineral Baths In: D. N. Kochankov. Sliven Mineral Baths, Sofia: Медицина и физкултура, 1962, p. 9