Technology to Bridge Formal and Informal Learning. Elsevier. 2013-02-08 [2021-12-23]. ISBN 9781780633626. (原始内容存档于2021-08-20) (英语). British Sundial, Society
(原始内容存档于2011-06-06). Sundial by John Whitehurst & Sons, 1812. flickr. [2011-06-01]. (原始内容存档于2017-01-08). - Museum label Bridge Hill House, Belper, Derbyshire