Buckalew, James O.; James, Maurice; Scott, Lisa; Reed, Paul (1998), Water Resources Assessment of Ecuador(PDF), Mobile District and Topographic Engineering Center, United States Army Corps of Engineers, p. 1, archived from the original(PDF) on 16 July 2011
Buckalew, James O.; James, Maurice; Scott, Lisa; Reed, Paul (1998), Water Resources Assessment of Ecuador(PDF), Mobile District and Topographic Engineering Center, United States Army Corps of Engineers, p. 1, archived from the original(PDF) on 16 July 2011