Columbia subject headings:
Electric lighting--Congresses.
Optics--Congresses.
Reflectors, Lighting--Congresses.
Solar collectors--Congresses.
Harvard subject headings:
Electric lighting--Congresses.
Optics--Congresses
Reflectors, Lighting--Congresses.
Solar collectors--Congresses.
Princeton subject headings:
Electric lighting--Congresses.
Optics--Congresses.
Reflectors, Lighting--Congresses.
Solar collectors--Congresses.