Não informado. Topographic and Geologic Atlas of Pennsylvania. Pennsylvania Geological Survey.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Topographic and Geologic Atlas of Pennsylvania. Harrisburg, Pa: Pennsylvania Geological Survey.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Topographic and Geologic Atlas of Pennsylvania. Pennsylvania Geological Survey.
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