WOOLLISCROFT, David J. Signalling and the design of the Gask Ridge system. Proceedings of the Society of Antiquaries of Scotland, [S. l.], v. 123, p. 291–313, 1994. DOI: 10.9750/PSAS.123.291.313. Disponível em: https://journals.socantscot.org/index.php/psas/article/view/9469. Acesso em: 18 jul. 2024.