Donchev, Slavi (1981). The Madara Horseman(PDF). Vol. 23–24. ICOMOS. pp. 41–46. Archived(PDF) from the original on 23 February 2017. Retrieved 18 April 2021.
"Boyana Church". UNESCO World Heritage Centre. Archived from the original on 18 April 2021. Retrieved 18 April 2021.
"Madara Rider". UNESCO World Heritage Centre. Archived from the original on 23 March 2021. Retrieved 18 April 2021.
Donchev, Slavi (1981). The Madara Horseman(PDF). Vol. 23–24. ICOMOS. pp. 41–46. Archived(PDF) from the original on 23 February 2017. Retrieved 18 April 2021.