Underground mine communications(in four parts) :
| Year: | 1977 |
|---|---|
| Document Type: | USBI |
| Issuing Agency: | U.S. Dept. of the Interior, Bureau of Mines, |
| Series: | Information circular - Bureau of Mines ; |
| Report Number: | 8745 |
| Subject: | Mine communication systems |
| Link: | https://hdl.handle.net/2027/mdp.39015078464230 |