Não informado. (1969). Pennsylvania Geology. Bureau of Topographic and Geologic Survey.
Style de citation Chicago (17e éd.)Não informado. Pennsylvania Geology. Harrisburg, Pa: Bureau of Topographic and Geologic Survey, 1969.
Style de citation MLA (8e éd.)Não informado. Pennsylvania Geology. Bureau of Topographic and Geologic Survey, 1969.
Attention : ces citations peuvent ne pas être correctes à 100%.
