Maxwell 2005, p. 19. Maxwell, Ingval (2005). "A History of Scotland's Masonry Construction". In Wilson, Peter (ed.). Building with Scottish stone. Edinburgh: Arcamedia. ISBN1-904320-02-3. OCLC183147671.
Noble 2006, p. 71. Noble, Gordon (2006). Neolithic Scotland: timber, stone, earth and fire. Edinburgh: Edinburgh University Press. ISBN0-7486-2338-8. OCLC71000487.
Noble 2006, p. 45. Noble, Gordon (2006). Neolithic Scotland: timber, stone, earth and fire. Edinburgh: Edinburgh University Press. ISBN0-7486-2338-8. OCLC71000487.
Barclay 1998, p. xii. Barclay, Gordon (1998). The Cleaven Dyke and Littleour: monuments in the Neolithic of Tayside. Edinburgh: Society of Antiquaries of Scotland. ISBN0-903903-13-X. OCLC41421691.
Noble 2006, p. 72. Noble, Gordon (2006). Neolithic Scotland: timber, stone, earth and fire. Edinburgh: Edinburgh University Press. ISBN0-7486-2338-8. OCLC71000487.
Noble 2006, p. 17. Noble, Gordon (2006). Neolithic Scotland: timber, stone, earth and fire. Edinburgh: Edinburgh University Press. ISBN0-7486-2338-8. OCLC71000487.
Moffat 2009, pp. 109–113. Moffat, Alistair (2009). Before Scotland: the story of Scotland before history. London: Thames & Hudson. ISBN0-500-28795-3. OCLC277068516.
Cunliffe 2005, p. 60. Cunliffe, Barry (2005). Iron Age communities in Britain : an account of England, Scotland and Wales from the seventh century BC until the Roman conquest. London: Routledge. ISBN0-415-34779-3. OCLC57719562.
Cunliffe 2005, p. 340. Cunliffe, Barry (2005). Iron Age communities in Britain : an account of England, Scotland and Wales from the seventh century BC until the Roman conquest. London: Routledge. ISBN0-415-34779-3. OCLC57719562.
Scarre 2002, p. 125. Scarre, Christopher (2002). Monuments and landscape in Atlantic Europe : perception and society during the Neolithic and early Bronze Age. London New York: Routledge. ISBN0-415-27314-5. OCLC264445949.
Cunliffe 2005, p. 325. Cunliffe, Barry (2005). Iron Age communities in Britain : an account of England, Scotland and Wales from the seventh century BC until the Roman conquest. London: Routledge. ISBN0-415-34779-3. OCLC57719562.
Cunliffe 2005, p. 322. Cunliffe, Barry (2005). Iron Age communities in Britain : an account of England, Scotland and Wales from the seventh century BC until the Roman conquest. London: Routledge. ISBN0-415-34779-3. OCLC57719562.
Lepage 2012, pp. 25 & 31. Lepage (2012). British fortifications through the reign of Richard III : an illustrated history. Jefferson, N.C: McFarland & Co. ISBN0-7864-5918-2. OCLC707825575.
Konstam 2010, p. 12. Konstam, Angus (2010). Strongholds of the Picts : the fortifications of dark age Scotland. Oxford Long Island City, NY: Osprey. ISBN1-84603-686-0. OCLC368021723.