Jenkins, Rome, 30 March 1755, acknowledging a letter from Lord Dartmouth of 27 December 1754: 'The case addressed to the Hon. Miss Legge, was that which contained the music, your Lordship's and Lord North's miniatures and some other articles' (HMC 15th Report, App. I, 1896, p. 169).
H. Walpole, Anecdotes of painting in England; 1760-1795, with some account of the principal artists; and incidental notes on other arts, Volume 5, London, 1937, p. 19. 'Mr. George Montagu has two heads in water-colours, painted by Pompeio at the same time, of Lord Dartmouth and Lord North.'
F. Russell, 'Portraits on the Grand Tour. Batoni's British Sitters', Country Life, CLIII, 7 June 1973, p. 1610, fig. 7 ('This is one of the few Batoni miniatures that can be traced... assured yet delicate in its small dimensions, shows how eloquent the painter was on such a scale').
E. P. Bowron, Pompeo Batoni and his British Patrons, London, 1982, p. 18, fig. 12 (as by Pompeo Batoni).
A. Clark, Pompeo Batoni Complete Catalogue, Oxford, 1985, fig. 180, cat. no. 194 (as by Pompeo Batoni).
J. Ingamells, National Portrait Gallery Mid-Georgian Portraits 1760-1790, London, 2004, pp. 219-220 ('Batoni also made half-length miniature versions in watercolour of each portrait [Ingamells is referring to Batoni's large-scale portraits of Lord North and Lord Dartmouth] which were dispatched from Rome late in 1754').
E. P. Bowron, Pompeo Batoni. A Complete Catalogue of his Paintings, New Haven and London, 2015, no. 193 (as by Pompeo Batoni).