Needham, J. (1974). «Astronomy in Ancient and Medieval China». Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences276 (1257): 67-82. JSTOR74275.". Philosophical Transactions of the Royal Society of London. «Series A,». Mathematical and Physical Sciences276 (1257)., The Place of Astronomy in the Ancient World (May 2, 1974), pp. 67–82. Accessed 9 Oct 2012.