Columbia subject headings:
Glass manufacture--Europe--Congresses.
Glassworkers--Congresses.
Glassworkers--Europe--Congresses.
Wages--Europe--Congresses.
Harvard subject headings:
Princeton subject headings:
Glass manufacture--Europe--Congresses.
Glassworkers--Congresses.
Glassworkers--Europe--Congresses.
Wages--Europe--Congresses.