D. N. Marshall. Carved Stone Balls(PDF). The Society of Antiquaries of Scotland. 1976/77, 108 [2020-09-15]. (原始内容存档(PDF)于2020-05-29).请检查|date=中的日期值 (帮助)
Lloyd 2012. Lloyd, David Robert. How old are the Platonic Solids?. BSHM Bulletin: Journal of the British Society for the History of Mathematics. 2012, 27 (3): 131–140. doi:10.1080/17498430.2012.670845.
National Museums of Scotland. Carved stone ball. [2008-03-22]. (原始内容存档于2013-07-02).
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D. N. Marshall. Carved Stone Balls(PDF). The Society of Antiquaries of Scotland. 1976/77, 108 [2020-09-15]. (原始内容存档(PDF)于2020-05-29).请检查|date=中的日期值 (帮助)