Metcalf, A. L. & Riskind, D. H. (1978). Four new species of Polygyra (Gastropoda, Pulmonata, Polygyridae) from Coahuila, Mexico. Proceedings of the Biological Society of Washington. 91:815–827.
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Metcalf, A. L. & Riskind, D. H.
1978
Four new species of Polygyra (Gastropoda, Pulmonata, Polygyridae) from Coahuila, Mexico
Proceedings of the Biological Society of Washington