| 其他書名 | An Overview of Present State of Development |
| 出版 | Department of Transportation, Federal Aviation Administration, Office of Aviation Policy, Policy Development Division, 1974 |
| URL | http://books.google.com.hk/books?id=L6hFju7QLuwC&hl=&source=gbs_api |
| EBook | FULL_PUBLIC_DOMAIN |