W. Armstrong, Lawrence, London, 1913, p. 167, as 'Vallecourt, Lady, perhaps an error for Valletort, Lady'. M.W. Brockwell, Sir Thomas Lawrence, P. R. A.: "Portrait of Sophia, Countess of Mount Edgcumbe", brochure, London, 1920, pp. 5-9. K. Garlick, Sir Thomas Lawrence, London, 1954, pp. 61, 75. M.F. Rogers Jr., 'A Mount Edgcumbe Portrait,' (Correspondence), Country Life, CXXIX, no. 3341, March 16, 1961, p. 595. K. Garlick, 'A Catalogue of the Paintings, Drawings and Pastels of Sir Thomas Lawrence,' The Annual Volume of the Walpole Society, XXXIX, 1962-1964, pp. 189, 292. The Toledo Museum of Art: European Paintings, Toledo, 1976, pp. 92-93, pl. 326. J.D. Morse, Old Master Paintings in North America, New York, 1979, p. 194. K. Garlick, Sir Thomas Lawrence: a complete catalogue of the oil paintings, Oxford, 1989, pp. 275-276, no. 784.