| Title | Window on Earth's interior |
| Publication Type | Journal Article |
| Year of Publication | 1976 |
| Authors | Ballard, RD |
| Journal | National Geographic Magazine |
| Volume | 150 |
| Pagination | 228–249 |
| ISSN | 0027-9358 |
| Keywords | HOV Alvin (Human Occupied Vehicle) |
| Title | Window on Earth's interior |
| Publication Type | Journal Article |
| Year of Publication | 1976 |
| Authors | Ballard, RD |
| Journal | National Geographic Magazine |
| Volume | 150 |
| Pagination | 228–249 |
| ISSN | 0027-9358 |
| Keywords | HOV Alvin (Human Occupied Vehicle) |