Frei, G. (2004). Cy Twombly. Thomas Ammann Fine Art.
Cita Chicago (17th ed.)Frei, Georg. Cy Twombly. Zurich: Thomas Ammann Fine Art, 2004.
Cita MLA (8th ed.)Frei, Georg. Cy Twombly. Thomas Ammann Fine Art, 2004.
Atenció: Aquestes cites poden no estar 100% correctes.