Hassall, Thomas. "Draft Letter to Elizabeth Marsden." Hassall Family Papers 1793-2000, vol. Series 2: Sub-series 4: correspondence, volume 4, 1811-1895. File 2: pp. 403-894, 1816-1866, State Library of New South Wales, 11 March 1818.
The catalogue guesses the date as being 1819. however, Thomas arrived in England in December 1817, and some markings on this draft letter at MS 594 suggest it may be dated March 11th.