Enock, Charles Reginald (1914) Ecuador: its ancient and modern history, topography and natural resources, industries and social development Charles Scribner's sons, New York, pages 177–178, OCLC2453173
Ziesler, R. and G.D. Ardizzone, G.D. (1979) "Amazon System"Las Aguas Continentales de America Latina / The Inland Waters of Latin America (COPESCAL Technical Paper No. 1) Fisheries and Aquaculture Department, Food and Agriculture Organization of the United Nations (FAO), Rome, ISBN92-5-000780-9, in English and Spanish
Enock, Charles Reginald (1914) Ecuador: its ancient and modern history, topography and natural resources, industries and social development Charles Scribner's sons, New York, pages 177–178, OCLC2453173