Robert Mangold, Perimeter Series, 1969–70, Crayon on paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/38272

Robert Mangold, Circle Drawing #2, 1973, Crayon and pencil on paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/37935

Robert Mangold, Circle Drawing #3, 1973, Crayon and pencil on paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/37936

Robert Mangold, Circle Drawing #4, 1973, Crayon and pencil on paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/37937

Robert Mangold, Circle Drawing #1, 1973, Crayon and pencil on paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/37933

Robert Mangold, Circle Drawing #6, 1973, Crayon and pencil on paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/37939

Robert Mangold, Circle Drawing #7, 1973, Crayon and pencil on paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/37940

Robert Mangold, Circle Drawing #8, 1973, Crayon and pencil on paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/37941

Robert Mangold, Circle Drawing #5, 1973, Crayon and pencil on paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/37938