| Author: | Hartwig, G. (Georg), 1813-1880 |
| Subject: | QE, Geology, Mines and mineral resources, Caves |
| Format: | Text |
| Date issued: | 2016 |
| Language: | English |
| Publisher: | Project Gutenberg, |
| Rights: | Public domain in the USA. |
| Download link: | The Subterranean World [electronic resource] / G. Hartwig |