| 其他書名 | A Study Made for U.S. Engineer Office, Pennsylvania in Connection with the Project Investigation |
| 出版 | War Department, Corps of Engineers, U.S. Army, St. Paul District Sub-Office, 1932 |
| URL | http://books.google.com.hk/books?id=DvdiZiYQFL0C&hl=&source=gbs_api |