G. Grappe, Catalogue du Musée Rodin, Paris, 1927, no. 143 (plaster version illustrated). H. Martinie, Auguste Rodin, Paris, 1949, no. 19 (another cast illustrated, p. 25). A.E. Elsen, Rodin, New York, 1963, pp. 52-53 (another version illustrated, p. 54). I. Jianou and C. Goldscheider, Rodin, Paris, 1967, p. 88, no. 11 (another version illustrated). J.L. Tancock, The Sculpture of Auguste Rodin, Philadelphia, 1976, pp. 111-112, 114 and 116 (another version illustrated, pp. 113 and 115). J. de Caso and P.B. Sanders, Rodin's Sculpture, A Critical Study of the Spreckels Collection, San Francisco, 1977, pp. 128-131 (another cast illustrated). A.E. Elsen, ed., Rodin Rediscovered, Washington, D.C., 1981, pp. 66-67 (another cast illustrated). A.E. Elsen, The Gates of Hell by Auguste Rodin, Stanford, California, 1985, pp. 71 and 73-74 (another cast illustrated). A.E. Elsen, Rodin's Thinker and the Dilemmas of Modern Public Sculpture, New Haven, 1985. C. Lampert, Rodin: Sculpture and Drawings, London, 1986, p. 24 (larger version illustrated, p. 25). A.E. Elsen, Rodin's Art, The Rodin Collection of the Iris & B. Gerald Cantor Center for the Visual Arts at Stanford University, New York, 2003, pp. 174-179, no. 38 (another cast illustrated, pp. 174-175, 178). A. Le Normand-Romain, The Bronzes of Rodin, Catalogue of Works in the Musée Rodin, Paris, 2007, vol. II, p. 586 (larger version illustrated).