| 其他書名 | Final Report Ordered by Legislature, 1891. A Summary Description of the Geology of Pennsylvania |
| 出版 | Board of Commissioners for the Geological Survey, 1895 |
| URL | http://books.google.com.hk/books?id=6ig0AQAAMAAJ&hl=&source=gbs_api |
| EBook | FULL_PUBLIC_DOMAIN |