Columbia subject headings:
Libraries--Austria--Vienna--History.
Libraries--Austria--Vienna--Statistics.
Libraries--History.
Library statistics.
Österreichische Nationalbibliothek.
Harvard subject headings:
Libraries--Austria--Vienna--History.
Libraries--Austria--Vienna--Statistics.
Libraries--History
Library statistics.
Österreichische Nationalbibliothek.
Princeton subject headings:
Libraries--Austria--Vienna--History.
Libraries--Austria--Vienna--Statistics.
Libraries--History.
Library statistics.
Österreichische Nationalbibliothek.