| Oldest Known Stone Tools Discovered. 3.3 Million Years Old - National Geographic | | National Geographic |
| Olduvai Gorge | Cambridge University Press | Louis Leakey |
| Olduvai Gorge Britannica | | Britannica Britannica |
| Olduvai Gorge Ngorongoro | | Ngorongoro Conservation Area Ngorongoro Conservation Area |
| Olduvai Gorge or Oldupai Gorge | | Noel Feans |
| Olduvai Gorge. The Skulls, Endocasts and Teeth of Homo habilis | Cambridge University Press | Phillip Tobias |
| Olduvai Gorge Volume 2.The Cranium and Maxillary Dentition of Australopithecus (Zinjanthropus) boisei | Cambridge University Press | Louis Leakey, Phillip Tobias |
| Olduvai Gorge Volume 3. Excavations in Beds I and II 1960 -1963 | Cambridge University Press | Mary Leakey |
| Olduvai Gorge Wikipedia | | Wikipedia Wikipedia |
| Olorgesailie 002 | | Jeffmugendi |
