| 其他書名 | A Co-operative Project of the Ohio Dept. of Education, Division of Elementary and Secondary Education, the Ohio State University, Natural Resources Institute, and Ohio Forestry Association |
| 出版 | Ohio Forestry Association, 1961 |
| URL | http://books.google.com.hk/books?id=vJ4vAAAAYAAJ&hl=&source=gbs_api |