J. Spence, Polymetis, Book 2, London 1747, pp. 96-100 and 111; Phillis Wheatley, 'Niobe in Distress for her Children' in Poems on Various Subjects, Religious and Moral, Boston, 12 June 1773; Booth Notes Doc. 5, p. 1; Farington Diary, vol. 5, p. 1754 (2 March 1802); vol. 6, p. 2062 (22 June 1803) & p. 2423 (7 October 1804); vol. 7, p. 2743 (2 May 1806); Boston Museum of Fine Arts, Catalogue of Paintings, 1921, no. 462 (attributed); Whitley 1800-1820, p. 296; [W. Pach et al.], exh.cat., New York, World's Fair, Masterpieces of Art, 1940, p. 110, no. 158; WGC, p. 162, pl. 18 (version 3 of P90B - lost Beaumont-National Gallery picture); R. Paulson, Literary Landscape Turner and Constable, 1982, p. 53, pl. 21; M. Paley, The Apocalyptic Sublime, 1986, p. 102, pl. 51; K. Baetjer, Glorious Nature: British Landscape Painting 1750-1850, 1993, p. 19; E.K. Waterhouse, Painting in Britain 1530-1790, 1994, p. 237, pl. 184 (re P90B); W. Vaughan, British Painting: The Golden Age, 1999, pp. 224-25, pl. 161 (re P90 - Yale Center for British Art version)