Bulgarian. [Архівовано 3 березня 2016 у Wayback Machine.] Report on the Current Status of United Nations Romanization Systems for Geographical Names. Compiled by the UNGEGN Working Group on Romanization Systems. Version 4.0, February 2013.
Bulgarian. [Архівовано 3 березня 2016 у Wayback Machine.] Report on the Current Status of United Nations Romanization Systems for Geographical Names. Compiled by the UNGEGN Working Group on Romanization Systems. Version 4.0, February 2013.