Rakadjiyska, Svetla Genova, Dyankov, Todor Konstantinov Via Pontica (Bulgaria) - from a Kaleidoscope of Cultural Attratcions for the Modern Tourist to a Cultural Attractions for the Modern Tourist to a Specialized Destination for Cultural Tourism,
Гея Либрис, 2012, pp. 25 - 29, 978-954-300-119-4.