Δεύτερη Βουλγαρική Αυτοκρατορία: Διαφορά μεταξύ των αναθεωρήσεων

* {{Cite web|url=http://fmg.ac/Projects/MedLands/BULGARIA.htm|title=Medieval Lands — Bulgaria|last=Cawley|first=Charles|website=|publisher=Hosted on the website of the Foundation for Medieval Genealogy|accessdate=26 February 2012}}

* {{Cite web|url=http://sitemaker.umich.edu/mladjov/files/bulgarian_rulers.pdf|title=Detailed List of Bulgarian Rulers|last=Mladjov|first=Ian|website=|publisher=|accessdate=26 February 2012}}

* {{Cite web|url=http://www.archivesforbalkans.bg/cgi-bin/e-cms/vis/vis.pl?s=001&p=0017&n=000001&g=|title=Грамота на цар Иван Асен ІІ, даваща свободен достъп на търговците от Дубровник във всички области на българското царство (1230 г.) (Charter of emperor Ivan Asen II giving free access to the merchants of Dubrovnik to all provinces of the Bulgarian Empire, 1230)|last=|first=|website=|publisher=Държавна агенция "Архиви" (State Agency "Archives"|language=βουλγαρικά|archiveurl=https://web.archive.org/web/20141108025637/http://www.archivesforbalkans.bg/cgi-bin/e-cms/vis/vis.pl?s=001&p=0017&n=000001&g=|archivedate=8 November 2014|dead-url=yes|accessdate=26 February 2012}}

* {{Cite web|url=http://www.bg-patriarshia.bg/index.php?file=history.xml|title=История на Българската православна църква (History of the Bulgarian Orthodox Church)|last=<!--Staff writer(s); no by-line.-->|website=Официален сайт на Българската патриарпия (Official Site of the Bulgarian Patriarchate)|language=βουλγαρικά|accessdate=2 February 2014}}