Columbia subject headings:
Galaxies--Clusters--Congresses.
Galaxies--Motion in line of sight--Congresses.
Superclusters--Congresses.
Harvard subject headings:
Galaxies--Clusters--Congresses
Galaxies--Motion in line of sight--Congresses.
Superclusters--Congresses.
Princeton subject headings:
Galaxies--Clusters--Congresses.
Galaxies--Motion in line of sight--Congresses.
Superclusters--Congresses.