Fritz Glarner, [Untitled], 1942, Charcoal on paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/34997

Fritz Glarner, Tondo, 1954, Charcoal on paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/38212

Fritz Glarner, Tondo, c. 1960, Conté crayon on paper, The Museum of Modern Art, New York. https://dartabase.art/cite/moma/38213