Haverfield, F.J. and MacDonald, G. 1910. Sir Robert Sibbald’s ’Directions for his honoured friend Mr Llwyd how to Trace and Remarke the Vestiges of the Roman Wall betwixt Forth and Clyde.’. Proceedings of the Society of Antiquaries of Scotland. 44, (Nov. 1910), 319–327. DOI:https://doi.org/10.9750/PSAS.044.319.327.