Ratzel, History of Mankind, Vol. III, pp. 407-412. London, 1896-1898.
Pliny, Natural History, Book VI, chap. 26.
Bunbury, History of Ancient Geography, Vol. II, pp. 351, 417-418, 470, 471. London, 1883.
For full discussion of Indian Ocean, see Helmolt, History of the World, Vol. II, pp. 580-584, 602-610. New York, 1902-1906. Duarte Barbosa, The Coasts of East Africa and Malabar, pp. 26-28, 41-42, 59-60, 67, 75, 79-80, 83, 166, 170, 174, 179, 184, 191-194, Hakluyt Society. London, 1866.
Pompeo Molmenti, Venice in the Middle Ages, Vol. I, pp. 117, 121-123, 130. Chicago, 1906. The Commercial and Fiscal Policy of the Venetian Republic, Edinburgh Review, Vol. 200, pp. 341-344, 347. 1904.
H.J. Mackinder, Britain and the British Seas, p. 24, note. London, 1904.
Hugonis Grotii, Mare Liberum sive de jure quod Batavis competit ad Indicana commercia dissertatio, contained in his De Jure Belli et Pacis. Hagae Comitis, 1680.