WOOLLISCROFT, David J; HOFFMANN, Birgitta. The Roman Gask System tower at Greenloaning, Perth & Kinross. Proceedings of the Society of Antiquaries of Scotland, [S. l.], v. 127, p. 563–576, 1998. DOI: 10.9750/PSAS.127.563.576. Disponível em: https://journals.socantscot.org/index.php/psas/article/view/9975. Acesso em: 26 apr. 2024.