J. M. Joass and T. Aitken, “The Brochs or Pictish Towers of Cinn-Trolla, Carn-Liath, and Craig-Carril, in Sutherland, with Notes on other Northern Brochs. With Report upon the Crania found in and about them”, arch-scot, vol. 5, pp. 95–130, Nov. 1891.