Columbia subject headings:
Alfonso X, King of Castile and Leon, 1221-1284--Congresses.
Astronomy--Early works to 1800--Congresses.
Astronomy--Tables--Early works to 1800--Congresses.
Harvard subject headings:
Astronomy, Arab--Congresses.
Castile (Spain)--History--Alfonso X, 1252-1284--Congresses.
Castile (Spain)--History--Alfonso X, 1252-1284.
Princeton subject headings:
Alfonso X, King of Castile and Leon, 1221-1284--Congresses.
Astronomy--Early works to 1800--Congresses.
Astronomy--Tables--Early works to 1800--Congresses.