Não informado. Topographic and Geologic Atlas of Pennsylvania. Pennsylvania Geological Survey.
Lua i Stíl Chicago (17ú heag.)Não informado. Topographic and Geologic Atlas of Pennsylvania. Harrisburg, Pa: Pennsylvania Geological Survey.
Lua MLA (8ú heag.)Não informado. Topographic and Geologic Atlas of Pennsylvania. Pennsylvania Geological Survey.
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