Rhodin, A.G.J.; Mittermeier, R.A. (1983). Description of Phrynops williamsi, a new species of chelid turtle of the South American complex. In Rhodin & Miyata (eds.): Advances in Herpetology and Evolutionary Biology. Cambridge, Mus. Comp. Zool. pp. 58-73.
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Rhodin, A.G.J.; Mittermeier, R.A.
1983
Description of Phrynops williamsi, a new species of chelid turtle of the South American complex.
In Rhodin & Miyata (eds.): Advances in Herpetology and Evolutionary Biology. Cambridge, Mus. Comp. Zool. pp. 58-73