(en) E. D. Cope et American Philosophical Society., Descriptions of extinct batrachia and reptilia from the Permian Formation of Texas /, American Philosophical Society,, (DOI10.5962/bhl.title.104569, lire en ligne)
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(en) E. D. Cope et American Philosophical Society., Descriptions of extinct batrachia and reptilia from the Permian Formation of Texas /, American Philosophical Society,, (DOI10.5962/bhl.title.104569, lire en ligne)