Columbia subject headings:
Harvard subject headings:
Antimatter--Congresses.
Positron annihilation--Congresses.
Resonance--Congresses.
Princeton subject headings:
Cosmochemistry--Congresses.
Galactic center--Congresses.
Positron annihilation--Congresses.
Positronium--Congresses.
Positrons--Scattering--Congresses.