Note 1 — Chapter I · The Development of Astronomical Thought to 1400 A.D. A Preliminary Sketch of Early Theories as a Background.
Reading edition
The earliest observation Ptolemy uses is an Egyptian one of an eclipse occurring March 21, 721 B.C. (Cumont: 7). [In these references, the Roman numerals refer to the volume, the Arabic to the page, except as stated otherwise. The full title is given in the bibliography at the back under the author's name.]