Columbia subject headings:
New York (N.Y.)--Social conditions--Pictorial works.
Subways--New York (State)--New York--Pictorial works.
Harvard subject headings:
Davidson, Bruce, 1933-
New York (N.Y.)--Social conditions--Pictorial works.
Subways--New York (State)--New York--Pictorial works.
Princeton subject headings:
Documentary photography.
New York (N.Y.)--Social conditions--Pictorial works.
Subways--New York (State)--New York--Pictorial works.