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Plummer & Scott |
1937 |
Upper Paleozoic ammonites in Texas.
The geology of Texas, vol.3 pt.1, Bull. Texas. Univ., 3701: 1-516, fig.1-88, pl.1-41; Austin, Texas.
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Tharalson |
1984 |
Revision of the Early Permian ammonoid family Perrinitidae.
Journal of Paleontology, 58 (3): 804-833, fig.1-24, 1tab.; Lawrence, Kansas.
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