Columbia subject headings:
Active galaxies--Congresses.
Galactic nuclei--Congresses.
Radio astronomy--Congresses.
Harvard subject headings:
Active galaxies--Congresses.
Astronomy
Astrophysics
Galactic nuclei--Congresses.
Physical geography.
Physics.
Quantum theory.
Radio astronomy--Congresses
Princeton subject headings:
Active galaxies--Congresses.
Galactic nuclei--Congresses.
Radio astronomy--Congresses.