Columbia subject headings:
Harvard subject headings:
Digital printing--History--20th century.
Printing industry--History--20th century.
Printing industry--Technological innovations--History--20th century.
Printing--Technological innovations--History--20th century.
Princeton subject headings:
Digital printing--History--20th century.
Printing industry--History--20th century.
Printing industry--Technological innovations--History--20th century.
Printing--Technological innovations--History--20th century.