G.G. Chisholm, Commercial Geography, p. 311. London, 1904.

Capt. A.T. Mahan, The Problem of Asia, pp. 41, 60, 120. New York, 1900.

Isabella B. Bishop, The Yangtze Valley and Beyond, Vol. I, pp. 97-98. New York and London, 1900.

E.C. Semple, Development of the Hanse Towns in Relation to their Geographic Environment, Bulletin Amer. Geog. Soc., Vol. 31. No. 3. 1899.

Nordenskiold, Voyage of the Vega, pp. 519-530, 552. New York, 1882. Anatole Leroy-Beaulieu, The Empire of the Tsars, Vol. I, Note pp. 278-281. New York, 1902.

Agnes Laut, Voyagers of the Northern Ocean, Harper's Magazine, January, 1906.

Alexis Krausse, Russia in Asia, pp. 21-54. New York, 1899.

Felix Dubois, Timbuctoo, pp. 198-190, 251-257. New York, 1896.

Ibid., p. 38.

D. Livingstone, Missionary Travels, pp. 71, 177. New York, 1858.