Columbia subject headings:
Byzantine Empire--Gazetteers.
Byzantine Empire--History.
Thrace--Gazetteers.
Thrace--History.
Harvard subject headings:
Byzantine Empire--Gazetteers.
Byzantine Empire--History.
Thrace--Gazetteers.
Thrace--History.
Princeton subject headings:
Byzantine Empire--Historical geography.
Thrace--Gazetteers.
Thrace--History.