Columbia subject headings:
Bulgaria--Antiquities.
Pliska (Bulgaria)--Antiquities.
Preslav (Bulgaria)--Antiquities.
Veliko Tŭrnovo (Bulgaria)--Antiquities.
Harvard subject headings:
Bulgaria--Antiquities.
Malko Tŭrnovo (Bulgaria)--Antiquities.
Pliska (Bulgaria)--Antiquities.
Preslav (Bulgaria)--Antiquities.
Princeton subject headings:
Art, Bulgarian.
Pliska (Bulgaria)--Antiquities.
Preslav (Bulgaria)--Antiquities.
Veliko Tŭrnovo (Bulgaria)--Antiquities.