GIBB, Andrew. Notes, with Sketches of Mason Marks on the Cathedral of St Machar, Old Aberdeen. Proceedings of the Society of Antiquaries of Scotland, [S. l.], v. 7, p. 471–473, 1867. DOI: 10.9750/PSAS.007.471.473. Disponível em: https://journals.socantscot.org/index.php/psas/article/view/5358. Acesso em: 3 may. 2024.