Columbia subject headings:
Interstellar hydrogen--Congresses.
Interstellar matter--Congresses.
Radio sources (Astronomy)--Congresses.
Stars--Evolution--Congresses.
Harvard subject headings:
H II regions (Astrophysics)--Congresses.
Interstellar hydrogen--Congresses.
Interstellar matter--Congresses.
Radio sources (Astronomy)--Congresses.
Stars--Evolution--Congresses
Princeton subject headings:
H II regions (Astrophysics)--Congresses.
Interstellar hydrogen--Congresses.
Interstellar matter--Congresses.
Radio sources (Astronomy)--Congresses.
Stars--Evolution--Congresses.