The local Indexes of Special Collections Division, Edinburgh University Library, George Square, show references to Steven related material (check the Indexes for more details): proofs of The history of the Scottish church in Rotterdam, published 1833, with the author's own corrections, at La.II.458; letter of Steven to D. Laing, 1838, at La.II.150; mention of Steven in a letter to D. Laing, 1858, at La.IV.18; mention of Steven in a letter of I. L. C. Jacob, in French, addressed from Rotterdam, to D. Laing, 1838, at La.IV.18; and, Steven mentioned in letters of Baron van Weitreenen van Tiellandt, to D. Laing, as the Director of Heriots Hospital, at La.IV.18.

In addition, the UK National Register of Archives (NRA), updated by the Historical Manuscripts Commission, notes: letters to Sir George Sinclair, 1841-1843, Private, Ref. NRA(S)0189/vol 12 NRA 10552 Sinclair.