An almost identical clock in the Palazzo Reale is illustrated in E. Colle and F. Mazzocca, Il Palazzo Reale, Milan, 2001, p. 291. Another example with purple veined marble was sold from the Property of Norvin Rinek; Christies, New York, 29 September 1999, lot 290. Another version with patinated bronze figures was sold anonymously at Christies, London, 17 April 1980, lot 130.