Columbia subject headings:
Architects--Labor unions--United States--Periodicals.
Chemical workers--Labor unions--United States--Periodicals.
Engineers--Labor unions--United States--Periodicals.
Industrial technicians--Labor unions--United States--Periodicals.
Industrial technicians--United States--Periodicals.
Harvard subject headings:
Chemical workers--Labor unions--United States--Periodicals.
Industrial technicians--Labor unions--United States--Periodicals.
Princeton subject headings: