MUNTZ, W.R.A. (1973)
Yellow filters and the absorption of light by the visual pigments of some amazonian fishes. Vision Research, 13 (12): 2235–2254
DOI: 10.1016/0042-6989(73)90225-3
MUNTZ, W.R.A. & CHURCH, E. & DARTNALL, H.J.A. (1973)
Visual Pigment of the Freshwater Stingray, Paratrygon motoro. Nature, 246 (5434): 517
DOI: 10.1038/246517a0
ALI, M.A. & ANCTIL, M. (1974)
Retinas of the electric ray (Narcine brasiliensis) and the freshwater stingray (Paratrygon motoro). Vision Research, 14 (7): 587–588
DOI: 10.1016/0042-6989(74)90048-0