Square Saint-Pierre, Paris (1887) by Vincent Van Gogh. Original from the Yale University Art Gallery. Digitally enhanced by… Free Image from public domain license 
Irises (1890) by Vincent Van Gogh. Original from the MET Museum. Digitally enhanced by rawpixel. Free Image from public domain license 
Irises (1889) by Vincent Van Gogh. Original from the J. Paul Getty Museum. Digitally enhanced by rawpixel. Free Image from public domain license 
Wheat Field with Cypresses (1889) by Vincent Van Gogh. Original from the MET Museum. Digitally enhanced by rawpixel. Free Image from public domain license