| 其他書名 | Twelve Types of Primary Activity Trips Across Nine Forest Service Regions |
| 出版 | U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station, 1990 |
| URL | http://books.google.com.hk/books?id=OonYCG_XlWUC&hl=&source=gbs_api |
| EBook | FULL_PUBLIC_DOMAIN |