Willebrord Snell in Archimedes to Hawking: Laws of Science and the Great Minds Behind Them (Clifford A. Pickover, 2008).
اطلع عليه بتاريخ 27 يونيو 2009.  Willebrord Snell in Archimedes to Hawking: Laws of Science and the Great Minds Behind Them (Clifford A. Pickover, 2008).