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Rewald, Sabine. "Cubism". In Heilbrunn Timeline of Art History. New York: The Metropolitan Museum of Art, 2000–. http://www.metmuseum.org/toah/hd/cube/hd_cube.htm (October 2004)
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Voorhies, James. "Surrealism". In Heilbrunn Timeline of Art History. New York: The Metropolitan Museum of Art, 2000–. http://www.metmuseum.org/toah/hd/surr/hd_surr.htm (October 2004)
Chapuis, Julien. "Gothic Art". In Heilbrunn Timeline of Art History. New York: The Metropolitan Museum of Art, 2000–. http://www.metmuseum.org/toah/hd/mgot/hd_mgot.htm (October 2002)
Clottes, Jean. "Chauvet Cave (ca. 30,000 B.C.)". In Heilbrunn Timeline of Art History. New York: The Metropolitan Museum of Art, 2000–. http://www.metmuseum.org/toah/hd/chav/hd_chav.htm (October 2002)
"Franciabigio (Francesco di Cristofano): Head of the Madonna" (32.100.89) In Heilbrunn Timeline of Art History . New York: The Metropolitan Museum of Art, 2000–. http://www.metmuseum.org/toah/works-of-art/32.100.89. (September 2011)
Galitz, Kathryn Calley. "Gustave Courbet (1819–1877)". In Heilbrunn Timeline of Art History. New York: The Metropolitan Museum of Art, 2000–. http://www.metmuseum.org/toah/hd/gust/hd_gust.htm (May 2009)
Hemingway, Colette and Seán Hemingway. "Art of the Hellenistic Age and the Hellenistic Tradition". In Heilbrunn Timeline of Art History. New York: The Metropolitan Museum of Art, 2000–. http://www.metmuseum.org/toah/hd/haht/hd_haht.htm (April 2007)
Rewald, Sabine. "Cubism". In Heilbrunn Timeline of Art History. New York: The Metropolitan Museum of Art, 2000–. http://www.metmuseum.org/toah/hd/cube/hd_cube.htm (October 2004)
The Editors of Encyclopædia Britannica. "Umberto Boccioni (Italian Painter)."Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 10 June 2014.
Voorhies, James. "Surrealism". In Heilbrunn Timeline of Art History. New York: The Metropolitan Museum of Art, 2000–. http://www.metmuseum.org/toah/hd/surr/hd_surr.htm (October 2004)