Columbia subject headings:
Harvard subject headings:
Absorption spectra--Congresses.
Galaxies--Spectra--Congresses.
Quasars--Spectra--Congresses.
Red shift--Congresses.
Princeton subject headings:
Absorption spectra--Congresses.
Galaxies--Spectra--Congresses.
Quasars--Spectra--Congresses.
Red shift--Congresses.