Harry Bouras, Chart 7B, 1970, Stamped colored ink,colored felt-tip pen, and pencil on paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/36843

Harry Bouras, Pertaining to Type B, 1970, Stamped ink, felt-tip pen, and pencil on paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/36847