Columbia subject headings:
Astronomy--Italy--History--19th century--Congresses.
Astronomy--Italy--History--20th century--Congresses.
Harvard subject headings:
Astronomy--Italy--History--19th century--Congresses.
Astronomy--Italy--History--20th century--Congresses.
Princeton subject headings:
Astronomy--Italy--History--19th century--Congresses.
Astronomy--Italy--History--20th century--Congresses.