| 其他書名 | The Variation of the Compass, from Observations Made in the United States Naval Service During the Period from 1881 to 1894 |
| 出版 | U.S. Government Printing Office, 1894 |
| URL | http://books.google.com.hk/books?id=fuAMAAAAYAAJ&hl=&source=gbs_api |
| EBook | FULL_PUBLIC_DOMAIN |