Barcellos, J.F.M. & Wood, C.M. & Val, A.L. (2006)
Ammonia and urea fluxes in Potamotrygon sp, a freshwater stingray of the Amazon. In The physiology of tropical fish. Symposium Proceedings, San Francisco: 33–37

Wood, C.M. & Matsuo, A.Y.O. & Wilson, R.W. & Gonzalez, R.J. & Patrick, M.L. & Playle, R.C. & Val, A.L. (2003)
Protection by natural blackwater against disturbances in ion fluxes caused by low pH exposure in freshwater stingrays endemic to the Rio Negro. Physiological and Biochemical Zoology, 76(1), 12–27
DOI: 10.1086/367946

Wood, C.M. & Matsuo, A.Y.O. & Gonzalez, R.J. & Wilson, R.W. & Patrick, M.L. & Val, A.L. (2002)
Mechanisms of ion transport in Potamotrygon, a stenohaline freshwater elasmobranch native to the ion-poor blackwaters of the Rio Negro. Journal of Experimental Biology, 205(19), 3039–3054