Columbia subject headings:
Impressionism (Art)
Painting, Modern--19th century--History and criticism.
Harvard subject headings:
Impressionism (Art)--France
Impressionism (Art)--Technique.
Painting, French--19th century
Painting--Technique
Plein air painting--Technique.
Princeton subject headings:
Impressionism (Art)--Technique.
Painting--Technique.
Plein air painting--Technique.