Columbia subject headings:
Civilization, Modern--19th century--Pictorial works.
Civilization, Modern--20th century--Pictorial works.
Photography, Artistic.
Photography, Stereoscopic.
Harvard subject headings:
Civilization, Modern--19th century--Pictorial works.
Civilization, Modern--20th century--Pictorial works.
Photography, Artistic
Photography, Stereoscopic
Princeton subject headings:
Civilization, Modern--19th century--Pictorial works.
Civilization, Modern--20th century--Pictorial works.
Keystone View Company--Photograph collections.
Photography, Artistic.
Photography, Stereoscopic.