| 其他書名 | A Preliminary Report. A Paper Presented Before the Montana Academy of Sciences Eighteenth Annual Meeting Held at Montana State University, Missoula, Montana, April 11-12, 1958 |
| 出版 | Bureau of Business and Economic Research, Montana State University, 1958 |
| URL | http://books.google.com.hk/books?id=sKIG1wRDTSUC&hl=&source=gbs_api |