Memorials of John McLeod Campbell, D.D., being selections from his correspondence, London, Macmillan and Co., (lire en ligne), p. 188
Family of Douglas, The Genealogy of the Families of Douglas of Mulderg and Robertson of Kindeace with their Descendants, Dingwall, A. M. Ross and Company, , 31–2 p. (lire en ligne)
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Royal Society (Great Britain), Proceedings of the Royal Society of London, (lire en ligne), p. 8