The Nuttall Encyclopedia
An affluent of the Amazon, which rises in Columbia; has a course of 1750 m., and is navigable to steamers for 970 m.
Wood, James, ed. Entry for 'Yapura'. The Nuttall Encyclopedia. https://www.studylight.org/encyclopedias/eng/nut/y/yapura.html. Frederick Warne & Co Ltd. London. 1900.