Woolliscroft, David, and Birgitta Hoffmann. “The Roman Gask System Tower at Shielhill South, Perthshire: Excavations in 1973 and 1996”. Proceedings of the Society of Antiquaries of Scotland 128 (November 30, 1999): 441-460. Accessed March 29, 2024. http://journals.socantscot.org/index.php/psas/article/view/10014.