Não informado. Topographic and Geologic Atlas of Pennsylvania. Pennsylvania Geological Survey.
Style de citation Chicago (17e éd.)Não informado. Topographic and Geologic Atlas of Pennsylvania. Harrisburg, Pa: Pennsylvania Geological Survey.
Style de citation MLA (8e éd.)Não informado. Topographic and Geologic Atlas of Pennsylvania. Pennsylvania Geological Survey.
Attention : ces citations peuvent ne pas être correctes à 100%.