The Nuttall Encyclopedia
One of the greater affluents of the Amazon; its head-waters rise in the Serra Diamantina, in the S. of Matto-Grosso State; has a northward course of over 1000 m. before it joins the Amazon; is a broad and excellent waterway, and navigable in its lower course for 150 m.
Wood, James, ed. Entry for 'Tapajos'. The Nuttall Encyclopedia. https://www.studylight.org/encyclopedias/eng/nut/t/tapajos.html. Frederick Warne & Co Ltd. London. 1900.