Found in articles
印度天文學
Sarma (2008), Astronomy in India The Vedas: An Introduction to Hinduism's Sacred Texts, Roshen Dalal, p.188 Subbarayappa, B. V. Indian astronomy: An historical
Early Development of Indian Astronomy'. In Selin, Helaine (编). Astronomy Across Cultures: The History of Non-Western Astronomy. Boston: Kluwer. 2000
Pingree, David, The Mesopotamian Origin of Early Indian Mathematical Astronomy, Journal of Historical Astronomy, 1973, 4 (1): 1–12, doi:10.1177/002182867300400102
皮克盾
the Maya Calendar. The Real Maya Prophecies: Astronomy in the Inscriptions and Codices. Maya Astronomy. 2002 [2007-06-18]. （原始内容存档于2007-06-02）. Miller
阿托盾
the Maya Calendar. The Real Maya Prophecies: Astronomy in the Inscriptions and Codices. Maya Astronomy. 2002 [2007-06-18]. （原始内容存档于2007-06-02）. Miller