Browne, G.F. 1900. Notice on a Cup-marked Boulder called the Saj di Gorone, or Stone of the Heel, near Stresa, on the Lago Maggiore. Proceedings of the Society of Antiquaries of Scotland. 34, (Nov. 1900), 297–299. DOI:https://doi.org/10.9750/PSAS.034.297.299.