SIMPSON, W Douglas. Invermark Castle. Proceedings of the Society of Antiquaries of Scotland, [S. l.], v. 68, p. 41–50, 1934. DOI: 10.9750/PSAS.068.41.50. Disponível em: https://journals.socantscot.org/index.php/psas/article/view/7899. Acesso em: 3 may. 2024.