Hartner, Willy. "The young Avestan and Babylonian calendars and the antecedents of precession." Journal for the History of Astronomy 10 (1979): 1. pp. 1–22. doi:10.1177/002182867901000102
jstor.org
Parker، R. A. (مايو 1974). "Ancient Egyptian Astronomy". Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences. ج. 276 ع. 1257: 51–65. JSTOR:74274.
uchicago.edu
penelope.uchicago.edu
T H Key, "A Dictionary of Greek and Roman Antiquities" (article Calendarium), London, 1875, available at [1].