Bell, C. 1875. Notes on South African Bored Stones, or Perforated Stone Balls, and a Hafted Stone Axe from South Australia, presented to the Museum; with Notice of Cave Paintings in South Africa. Proceedings of the Society of Antiquaries of Scotland. 11, (Nov. 1875), 140–145. DOI:https://doi.org/10.9750/PSAS.011.140.145.