For more on the establishment of direct sailing routes from Egypt to India, ancient knowledge of the monsoon winds, and details about Eudoxus and Hippalus, see: Hourani, George F. (1995). Arab Seafaring in the Indian Ocean in Ancient and Early Medieval Times. Princeton University Press. pp. 24–26. ISBN0-691-00032-8.; online at Google Books
Tozer, Henry F. (1997). History of Ancient Geography. Biblo & Tannen. pp. 189–190. ISBN0-8196-0138-1.; online at Google Books
Tozer, Henry F. (1997). History of Ancient Geography. Biblo & Tannen. pp. xxiii. ISBN0-8196-0138-1.; online at Google Books