Possible Clues:

• Some Louvre paintings
• 'Luncheon on the Grass' and others
• Some French Impressionist works
• Some Impressionist pieces
• Some French paintings
• Some Impressionist works
• Certain portraits of Zola, Chabrier and Mallarmé
• 'The Luncheon on the Grass' and 'Olympia'
• "The Luncheon on the Grass" and "Olympia," e.g
• Some Musée d'Orsay works